The invention also relates to a method for dyeing keratin fibres, and in particular human keratin fibres, using the multiple-compartment device. Throughout the years, people have sought to modify the colour of their skin, their eyelashes or their hair. Several techniques have been developed to achieve the desired colour. A first method for dyeing human keratin fibres implies dye compositions containing oxidation dye precursors, generally known as oxidation bases. These oxidation bases are colourless or weakly coloured compounds, which, when combined with oxidizing products, may give rise to coloured compounds via a process of oxidative condensation. The shades obtained with these oxidation bases can be modified by combining them with couplers or coloration modifiers. The variety of molecules used as oxidation bases and couplers allows a wide range of colours to be obtained. A second method for dyeing human keratin fibres is known as direct dyeing or semi-permanent dyeing, and comprises the application of direct dyes, which are coloured and colouring molecules that have affinity for fibres. Given the nature of the molecules used, they tend rather to remain on the surface of the fibre and penetrate relatively little into the fibre, when compared with the small molecules of oxidation dye precursors. The main advantages of this type of dyeing are that it does not require any oxidizing agent, which limits the degradation of the fibres, and that it does not use any dyes that have particular reactivity, resulting in limitation of the intolerance risks, Two of the most well known natural dyes are those derived from the henna and the indigo producing plants. Both henna and indigo continue to be used in feminine beauty enhancement for colouring the hair, the nails and the skin. For instance, henna is used Tor temporary skin tattoos. In addition, indigo and henna are both used for dyeing fabrics (jeans), leather, silk and wool, etc. Henna is also traditionally used for various important events, celebrations and beliefs. Henna affords an orange-red coloration on grey hair, and a "warm" i.e. coppery to red colour on chestnut-brown hair, while indigo affords a blue coloration on grey hair, and a "cold" colour of ash to violet colour on chestnut-brown hair. However, the dyeing processes using henna and/or indigo are difficult to perform and face several drawbacks. Indeed, a kind of "paste" (often referred to as a "poultice") is first made from ground or powdered leaves, which is then diluted at the time of use with warm water, and the said paste is then applied to the keratin fibres. Most of the time, these colorants require overnight soaking in warm water, to get the ideal consistency of the paste imparting best perceived coloration on the hair. Hence the preparation of this paste may be time consuming. Moreover, during the preparation and application of the composition to keratin fibres, it is not always possible to obtain satisfactory impregnation due to the poor consistency of the composition obtained from the coarsely ground powder. Indeed, during mixing and soaking, lumps form and are then difficult to break. It is also very difficult to hope to reproduce the shades exactly, since the henna and/or indigo contents very often vary from one batch to another and between different ground materials. Therefore, the consumer has to adjust the amount of water to the amount of powder in order to get the appropriate shade, Added to this, are the risks of staining the cloths and the skin with henna or indigo during the preparation of the "paste" and also during its application to the keratin fibres, since the consistency is very irregular. The preparation requires also extra bowl and brushes, which increase the price for the consumers. In conclusion, the preparation and the dyeing processes using henna and/or indigo are not only elaborate but also expensive and time consuming. Thus, there is a real need to develop a product allowing dyeing methods involving natural plant powder, especially henna and/or indigo powder not to have the combination of drawbacks previously described, i.e. which are namely more convenient, time-saving and easier to implement than conventional dyeing methods while being capable of delivering satisfactory coloration, for example powerful and intense colorations, with a wide variety of color shades.The Applicant has now discovered that these aims and others could be achieved by a multiple-compartment device composed of a closed envelop divided in at least two distinct compartments separated from one another by at least one internal frangible seal, wherein at least one the compartments contains a composition (A), comprising at least one natural plant powder, especially henna plant powder and/or indigo plant powder, and the second compartment contains an aqueous composition (B) comprising at least one direct dye, more preferably at least one anionic direct dye . The present invention therefore relates to a multiple-compartment device composed of a closed envelop, made of at least two flexible sidewalls secured together along their peripheral edges, defining a sealed perimeter and an internal volume; said internal volume being divided in at least two distinct compartments, separated from one another by at least one internal frangible seal, wherein at least one of the compartments contains a composition (A), comprising at least one natural plant powder and the second compartment contains an aqueous composition (B) comprising at least one direct dye, more preferably at least one anionic direct dye . The multiple-compartment device according to the present invention is convenient, easy to handle and time-saving. Indeed, the frangible seal is easily broken by pressing one of the compartments. The natural plant powder is then instantly mixed with the aqueous composition within the closed envelop. A very nice creamy and homogeneous paste is obtained, which when applied to the hair gives the appropriate color in an application time of one hour. In addition, the multiple-compartment device according to the present invention allows the balanced amounts of water and natural plant powder. In other words, the multiple-compartment device according to the present invention is self-sufficient. No external product, such as additional water, is required. As soon as the internal frangible seal is broken, the dyeing composition is instantly mixed and obtained within the closed envelop. No soaking time is required. The dyeing composition can directly be applied on the keratin fibres. Besides, thanks to this direct preparation within the enclosed envelop, the risk of staining clothing is avoided. The consumer does not need to pour the preparation in an extra bowl and mix it with b r u s h e s. The present invention provides also better dyeing properties than the traditional method, especially powerful, intensive and/or chromatic coloration, with a wide variety of color shades in a shorter time. Furthermore, hair dyed with the paste obtained by the multiple-compartment device of the present invention exhibits good cosmetic properties, such as suppleness, smoothness, shine, detangling, volume, discipline and capability to be individualized. In particular, hair dyed with the paste obtained by the multiple-compartment device according to the invention shows improved suppleness, smoothness and coated feel than hair dyed with a paste obtained by mixing natural plant powder, especially henna and/or indigo powder, direct dye(s), especially anionic direct dye(s) and warm water. Another object of the present invention concerns a method for dyeing keratin fibres, and in particular human keratin fibres, wherein the following steps are successively performed: - applying a sustained pressure to the closed envelop in the region of at least one compartment of a multiple-compartment device as previously defined, in order to break the internal frangible seal, - opening the closed envelop of said multiple-compartment device, and - applying the mixture of compositions (A) and (B), as defined previously, on said keratin fibres. Other subjects, characteristics, aspects and advantages of the invention will emerge even more clearly on reading the description and the examples that follow, with reference to the drawings, in which: - Figure 1 schematically shows an example of multiple-compartment device according to the invention; and - Figure 2 shows a variant embodiment of the multiple-compartment device from Figure 1. In which that follows and unless otherwise indicated, the limits of a range of values are included within this range, in particular in the expressions "of between" and "ranging from...to...". Moreover, the expression "at least one" used in the present description is equivalent to the expression "one or more". The term "flexible" is used to describe a material, which deforms, but does not break, under the pressure exerted by a user. This term is not synonymous with the term "elastic". In other words, the term "flexible" is used to describe an element which bends without stretching and without plastic deformation under the action of a force exerted by a user generating a torque typically higher than 0.001 N.m, and which moves back to its position of rest when the pressure is released. On the contrary, the terms "stiff" and "not deformable" are used to describe an element which does not almost bend under the effect of a strength exercised by a user typically generating a torque lower than 0.05 N.m, The term "sheet'1 is synonymous with the term "layer". The multiple-compartment device As illustrated in Figure 1, a multiple-compartment device 1 is composed of a closed envelop 2, made of at least two flexible sidewalls 3a and 3b secured together along their peripheral edges 4, defining a sealed perimeter 5 and an internal volume 6, which is divided in at least two distinct compartments 7a and 7b, separated from one another by at least one internal frangible seal 8. According to the present invention, at least one of the compartments 7a contains a composition (A), comprising at least one natural plant powderand the second compartment 7b contains an aqueous composition (B) comprising at least one direct dye. In other words, the compartment 7a containing the composition (A) is separated from the compartment 7b containing the aqueous composition (B) by the internal frangible seal 8. Compositions (A) and (B) are thus contained in two different compartments 7a and 7b and, cannot commingle together. Preferably, the multiple-compartment device 1 is divided into two distinct compartments 7a and 7b. The sealed perimeter 5 has a first end 9, a second end 10, and two opposed sides 11 and 12. Preferably, the sealed perimeter 5 has a width of between 5 to 15 mm. Each flexible sidewall 3a and 3b is made of at least one sheet of polymeric film. The sheet of polymeric film can be either a single layer or a multilayer polymeric film. The layers of polymeric film may be different in structure. The length of the sidewalls 3a and 3b preferably ranges from 100 to 200 mm, and more preferentially from 120 to 160 mm. The width of the sidewalls 3a and 3b preferably ranges from 100 to 200 mm, and more preferentially from 120 to 200 mm. The length of the first compartment 7a preferably ranges from 5 to 200 mm, and more preferentially from 80 to 150 mm. The length of the second compartment 7b preferably ranges from 5 to 200 mm, and more preferentially from 80 to 150 mm. The length of the first compartment 7a maybe higher than the length of the second compartment 7b but it is preferably equal to the length of the second compartment 7b. According to a preferred embodiment, the closed envelop 2 is made of at least one sheet of polymeric film folded back on itself and sealed at its peripheral edges. In other words, according to this particular embodiment, the two flexible sidewalls 3a and 3b are made of the same sheet of polymeric film, which can be either a single layer or a multilayer polymeric film. Preferably the sheet of polymeric film is a multilayer polymeric film comprising at least two, different or identical, layers of polymeric film. Thus, the sheet of polymeric film has a laminate structure and the layers of polymeric film are superposed on one another. A second sheet can optionally be made of paper. The sheet of polymeric film suitable for the present invention is preferably prepared from polyvinyl chloride (PVC), polyesters, polyolefins, polyamides, or polystyrenes. Examples of polyvinyl chloride (PVC) are vinyl polymers containing vinyl chloride units in their structure, such as copolymers of vinyl chloride with vinyl esters of aliphatic acids, copolymers of vinyl chloride with esters of acrylic or methacrylic acid or with acrylonitrile, copolymers of vinyl chloride with diene bonds and unsaturated dicarboxylic acids or anhydrides thereof, copolymers of vinyl chloride and vinylidene chloride with unsaturated aldehydes, ketones, etc., or polymers and copolymers of vinylidene chloride with vinyl chloride or other polymerizable compounds. The thermoplastics based on vinyl can also be rendered flexible in a manner known per se by means of primary or secondary plasticizers. The PVC sheets can, as the case may be, also be drawn monoaxially (oPVC) or biaxially. Examples of polyesters are poly(alkylene terephthalate)s or poly(alkylene isophthalate)s having alkyl groups or radicals containing from 2 to 10 carbon atoms or alkyl groups containing from 2 to 10 carbon atoms which are interrupted at least by one -0-, such as, for example, poly(ethylene terephthalate) (PET sheets), poly(propylene terephthalate), poly(butylenes terephthalate) (poly(tetramethylene terephtalate)), poly(decamethylene terephthalate), poly(l,4- cyclohexyldimethylol hterephthalate) or poly(ethylene 2,6 naphthalenedicarboxylate), or copolymers of poly(alkylene terephthalate) and poly(alkylene isophthalate), the proportion of isophthalate being, for example, from 1 to 10 mol%, copolymers and terpolymers, and also block polymers and grafted alternative forms of the abovementioned substances. Other appropriate polyesters, such as polyethylene naphthalate, are known in the technical field under the abbreviation PEN. Other polyesters are copolymers of terephthalic acid and of another polycarboxylic acid with at least one glycol. Copolyesters of terephthalic acid, of ethylene glycol and of an additional glycol are appropriate. Glycol-modified polyesters, which are known in the technical field under the name PETG, are preferred. Appropriate polyesters are composed of poly(alkylene terephthalate)s having alkyl groups or radicals comprising 2 to 10 carbon atoms and poly(alkylene terephthalate)s having alkyl groups or radicals containing 2 to 1 0 carbon atoms which are interrupted by 1 or 2 -0-. Other preferred polyesters are poly(alkylene terephthalate)s having alkyl groups or radicals containing 2 to 4 carbon atoms and preference is very particularly given to poly(ethylene terephthalate)s. These poly(ethylene terephthalate)s also include A-PET, PETP and the PETG mentioned or the G-PET. Examples of polyolefins are polyethylenes (PE), for example high density polyethylene (HDPE, density of greater than 0.944 g/cm3), medium density polyethylene (MDPE, density of 0.926 to 0.940 g/cm3), linear medium density polyethylene (LMDPE, density of 0.926 to 0.940 g/cm3), low density polyethylene (LDPE, density of 0.910 to 0.925 g/cm3) and linear low density polyethylene (LLDPE, density of 0.916 to 0.925 g/cr3), for example in the form of nonoriented sheets (PE sheet) or monoaxially or biaxially oriented sheets (oPE sheet), polypropylenes (PP), such as axially or biaxially oriented polypropylene (oPP sheet) or cast polypropylene (cPP sheet), amorphous or crystalline polypropylene or blends thereof or atactic or isotactic polypropylene or blends thereof, poly(l-butene), poly(3-methylbutene), poly(4-methylpentene) and copolymers thereof, then polyethylene with vinyl acetate, vinyl alcohol or acrylic acid, such as, for example, ionomer resins, such as copolymers of ethylene, of acrylic acid, of methacrylic acid, of acrylic esters, tetrafluoroethylene or polypropylene, in addition random copolymers, block copolymers or olefin polymer/elastomer blends. The polyolefin materials can also comprise cycloolefins as monomer of a homopolymer or of copolymers. Preference is given to high density polyethylenes and to polypropylenes, and also to ionomers, for example known under the trade name Surlyn and sold by the company Dupont de Nemours. Examples of polyamides (PA) for the polymeric film are composed, for example, of polyamide 6, s-caprolactam homopolymer (polycaprolactam); polyamide 11; polyamide 12, co-lauryllactam homopolymer (polylauryllactam); polyamide 6,6, homopolycondensate of hexamethylenediamine and of adipic acid (poly(hexamethylene adipamide)); polyamide 6,10, homopolycondensate of hexamethylenediamine and of sebacic acid (poly(hexa-methylene sebacamide); polyamide 6,12, homopolycondensate of hexamethylenediamine and ofdodecanedioic acid (poly(hexamethylene dodecanamide)) or polyamide 6-3-T, homopolycondensate of trimethylhexamethylenediamine and of terephthalic acid (poly(trimethylhexamethylene terephthalamide)), and blends thereof. The polyamide sheets are drawn monoaxially or biaxially (oPA). Examples of polystyrenes for the polymeric film are composed, for example, of oriented polystyrene, in particular mono- or biaxially oriented polystyrene, which may be produced by stretching extruded polystyrene film or polystyrene copolymerized with butadiene. Preferentially, the sheet of polymeric film is chosen from poly(alkylene terephthalate) and polyolefins, and more preferentially from poly(ethylene terephthalate), polyethylene and ionomers, such as copolymer of polyethylene and methacrylic acid, and polystyrene such as oriented polystyrene, The thickness of polymeric films ranges from 60 urn to 200 \xm and preferably from 80 um to 140 um, The internal frangible seal 8, according to the present invention, is comprised in the internal volume 6. Each ends 13 of the internal frangible seal 8 is connected to at least one edge 4 of the sealed perimeter 5. As illustrated in Figure 1, one of the ends 13 of the internal frangible seal 8 is connected to the first end 9, while the other end 13 of the internal frangible seal 8 is connected to the second end 10 of the sealed perimeter 5, The expressions "seal" or "sealed perimeter", according to the present invention, refer to a definitive bond between two sheets of polymeric film or between two parts of a sheet folded back on itself. This seal can be obtained fusing and/or mixing together the two sheets or the two parts. In other words, the seal between the two sheets or the two parts cannot be opened without damaging the walls formed by the two sheets or by the two parts. The expression "frangible seal", according to the present invention, refers to a non definitive bound between two sheets of polymeric film. In other words, the frangible seal can be opened without damaging the walls formed by the two sheets. The internal frangible seal 8 is formed by heat-sealing or ultrasonic-sealing process the internal layers of the sidewalls 3a and 3b. In other words, the internal parts of polymeric film(s) forming the sidewalks 3a and 3b are sealed together in order to create the internal frangible seal 8. The internal frangible seal 8 provides impermeability between the two compartments 7a and 7b, avoiding the composition (A) contained in one of the compartment 7a to mix with the aqueous composition (B) contained in the second compartment 7b. However, when a consumer applies a pressure to the closed envelop 2 in the region of a compartment (first compartment 7a or second compartment 7b), the internal frangible seal 8 breaks under the force of the pressure transmitted by the composition contained in the compartment to the frangible seal. The compositions (A) and (B) contained in both compartments can pass from one compartment to the other through the broken seal, and can thus mix together. The internal frangible seal thus requires two conflicting performance. On the first hand, the internal frangible seal provides a relatively strong resistance to a force generated during normal storage or handling, in order to avoid inadvertent rupture of the seal. And on the second hand, the internal frangible seal shall be completely broken upon user activation, in order to avoid restriction of the flow path between the two compartments, inducing thus an unsatisfactory mixing of compositions (A) and (B). The force pressure to apply in order to break the internal membrane in between the two compartments ranges from 0.5 kg/cm2 to 3 kg/cm2. The multiple-compartment device 1 may also comprise an opening means, for example by way of tearing or cutting with a pair of scissors. According to a preferred embodiment, the opening means is a pre-cut line 14 parallel to the first end 9 of the sealed perimeter 5, as illustrated in Figure 1. The pre-cut line 14 can be produced by laser, and can then be torn easily without a tool. Figure 2 illustrates a variant embodiment of a multiple-compartment device 1 in the form of a stand-up device. The respective 12 elements comprising this embodiment are identified by using the corresponding reference numbers used for the description of the multiple-compartment device in Figure 1, This particular embodiment differs from the device disclosed in 5 Figure 1 in that the second end 10 of the sealed perimeter 5 has a bottom 15 and involves a folded gusset structure 16 allowing the multiple-compartment device 1 to be freestanding, At the first end 9, as well as at the two opposed sides 11 and 12, the sheet of polymeric film can be sealed without gusset. Such an 10 embodiment may involve a more complex sealed perimeter 5 to create the gusset 16 and the bottom 15. Composition (A) The composition (A) according to the present invention 15 comprises at least one natural plant powder, The natural plant powder of composition (A) can be chosen from henna plant powder, indigo plant powder, annatto plant powder, carotenoid powder coming from Chilies and carrots, Lutein and zeaxanthin powder coming from Marigold flower, Curcumin extract coming from turmeric, 20 Chlorophyll and Chorophyllin extract coming from green grass, Blue Anthocyanin extract from butterfly pea flower, Betanin extract from beetroot, Safflower extract ,Turmeric powder O/S and W/S, Lutein W/D, Ratanjyot powder and mixtures thereof. According to an embodiment, the natural plant powder is 25 preferably chosen from henna plant powder, indigo plant powder or mixtures thereof. The henna plant powder used in the present invention is preferably red henna (Lawsonia inermis, alba). Red henna consists of leaves of shrubs of the genus Lawsonia 30 from the family of Lythraceae, which is based on the principle of dyeing with the active agent lawsone: 2-hydroxy-l,4-naphthoquinone, Lawsone [83-72-7] (CI Natural Orange 6 ; CI 75420), also known as isojuglonc, may be found in henna shrubs {Lawsonia alba, Lawsonia 13 inermis) ("Dyes, Natural", Kirk-Othmer Encyclopedia of Chemical Technology, "Henna" Encyclopedia Britannica). Indigo used in the present invention is a natural dye, originating from indigo-producing plants, and corresponds to the The indigo plant powder used in the present invention is preferably obtained from at least one indigo-producing plant chosen 10 from the following genera: - Indigofera such as Indigofera tinctoria, Indigo suffruticosa, Indigofera articulata, Indigofera arrecta, Indigofera gerardiana, Indigofera argenta, Indigofera indica, Indigofera longiracemosa; - Isatis such as Isatis tinctoria; 15 - Polygonum or Persicaria such as Polygonum tinctorum (Persicaria tinctoria): - Wrightia such as Wrightia tinctoria; - Calanthe such as Calanlhe veratrifolia; and - Baphicacanlhus such as Baphicacanthus citsia. 20 According to a preferred embodiment, the indigo-producing plant is chosen from the genus Indigofera, and is more particularly Indigofera tinctoria, Use may be made of all or part of the indigo-producing plant, Preferably, indigo is prepared from the leaves of the plant, and more 25 particularly from the leaves of Indigofera tinctoria. It is understood that the natural plant powder used in the present invention are different from an extract. Specifically, an extract is a product of maceration in solvents, generally organic solvents, whereas the powder according to the 30 invention is a pure natural product originating from henna or indigo- 14 producing plants, reduced by grinding or other mechanical means, into fine particles. The composition (A) of the present invention comprises natural plant, especially henna plant and/or indigo plant, in powder form, 5 especially , preferably as fine particles, relative to the total weight of said composition (A). The natural plant powders may be screened to obtain particles with upper limit sizes corresponding to the orifices or mesh sizes of the screen particularly between 35 and 80 mesh (US). 10 According to one particular mode of the invention, the size of natural plant powder particles is fine. According to the invention, a particle size of less than or equal to 500 (.im is more particularly intended. Preferentially, the powder consists of fine particles with sizes inclusively between 50 and 300 urn and more particularly 15 between 10 and 200 urn. It is understood that the said natural plant particles preferentially have a moisture content of between 0 and 10% by weight, relative to the total weight of the powder. The natural plant powder, present in composition (A) according 20 to the invention is preferably chosen from red henna powder of Lawsonia, Indigofera tinctoria, and mixtures thereof. The amount of natural plant powder, in the present invention, is preferably greater than or equal to 50% by weight, more preferably greater than or equal to 60% by weight, and better still greater than or 25 equal to 70% by weight, relative to total weight of the composition (A). Itcan range from 50 to 99%, preferably from 60 to 95%, better still from 70 to 90% by weight, relative to total weight of the composition 30 Additional dyes: Composition (A) according to the present invention as defined previously may also contain one or more additional direct dyes other than the natural plant powder. 15 These direct dyes are chosen, for example, from those conventionally used in direct dyeing, and among which mention may be made of any commonly used aromatic and/or non-aromatic dyes such as neutral, acidic or cationic nitrobenzene direct dyes, neutral, 5 acidic or cationic azo direct dyes, natural direct dyes, neutral, acidic or cationic quinone and in particular anthraquinone direct dyes, azine, triarylmethane, indoamine, methine, styryl, porphyrin, metalloporphyrin, phthalocyanine, cyanine and methine direct dyes, and fluorescent dyes. 10 The natural or non-natural direct dye(s), other than the natural plant powder a), in the composition (A) according to the invention particularly represents from 0.001% to 10% by weight relative to the total weight of the composition and even more preferentially from 0.05% to 5% by weight relative to the total weight of the composition 15 under consideration. Preferably, composition (A) of the invention does not contain any synthetic direct dyes, i.e. dyes that do not occur in nature. According to an embodiment, composition (A) of the invention does not contain any additional direct dye, other than henna powder. 20 According to an embodiment, composition (A) of the invention does not contain any additional direct dye, other than the natural plant powder. The composition (A) according to the present invention may further comprise one or more fatty substance(s), preferably non- 25 silicone fatty substance(s). The term "fatty substance" means an organic compound that is insoluble in water at ordinary ambient temperature (25°C) and at atmospheric pressure (760 mmHg), with a solubility in water of less than 5%, preferably less than 1% and even more preferentially less 30 than 0.1%. The non-silicone fatty substances generally have in their structure a hydrocarbon-based chain comprising at least 6 carbon atoms. In addition, the fatty substances are generally soluble in organic solvents under the same temperature and pressure conditions, 16 for instance chloroform, ethanol, benzene, liquid petroleum jelly or decam ethyl eye 1 ope ntasiloxane. The non-silicone fatty substance(s) of the invention is (are), moreover, nonpolyoxyethylenated and nonpolyglycerolated. 5 The term "non-silicone fatty substance" means a fatty substance of which the structure does not comprise any silicon atoms. The fatty substance(s) may be liquid or non-liquid at ambient temperature and at atmospheric pressure. The liquid fatty substances of the invention preferably have a viscosity of less than or equal to 2 10 Pa.s, better still less than or equal to 1 Pa.s and even better still less than or equal to 0.1 Pa.s at a temperature of 25°C and at a shear rate of 1 s->. The liquid fatty substance(s), preferably liquid non-silicone fatty substance(s) used in the present invention is (are) in particular 15 chosen from hydrocarbons, fatty alcohols, esters of fatty acid and/or of fatty alcohol, non-salified fatty acids, having a fatty chain, and mixtures thereof. The term "liquid hydrocarbon" means a hydrocarbon composed solely of carbon and hydrogen atoms, which is liquid at standard 20 temperature (25°C) and at atmospheric pressure (760 mmHg, i.e. 1.013 x 105 Pa). More particularly, the liquid hydrocarbons are chosen from: - linear or branched, optionally cyclic, C6-C16 alkanes. Examples that may be mentioned include hexane, undecane, dodecarie, 25 tridecane, and isoparaffins, for instance isohexadecane, isododecane and isodecane, - linear or branched hydrocarbons, of mineral, animal or synthetic origin, with more than 16 carbon atoms, such as liquid paraffins, and derivatives thereof, petroleum jelly, liquid petroleum 30 jelly, polydecenes, hydrogenated polyisobutene such as the product sold under the brand name Parleam® by the company NOF Corporation, and squalane. 17 Preferably, the liquid hydrocarbon(s) is (are) chosen from liquid paraffins, isoparaffins, liquid petroleum jelly, undecane, tridecane, isododecane, and mixtures thereof. In one preferred variant, the liquid hydrocarbon(s) is (are) 5 chosen from liquid petroleum jelly, isoparaffins, isododecane, and a mixture of undecane and of tridecane. The term "liquid fatty alcohol" means a nonglycerolated and nonoxyalkylenated fatty alcohol, which is liquid at standard temperature (25°C) and at atmospheric pressure (760 mmHg, i.e. 1.013 10 x io5 Pa). Preferably, the liquid fatty alcohols of the invention comprise from 8 to 30 carbon atoms. The liquid fatty alcohols of the invention may be saturated or unsaturated. 15 The saturated liquid fatty alcohols are preferably branched. They may optionally comprise in their structure at least one aromatic or non-aromatic ring. They are preferably acyclic. More particularly, the saturated liquid fatty alcohols of the invention are chosen from octyldodecanol, isostearyl alcohol and 2- 20 hexyldecanol, Octyldodecanol is most particularly preferred. The unsaturated liquid fatty alcohols contain in their structure at least one double or triple bond, and preferably one or more double bonds. When several double bonds are present, there are preferably 2 25 or 3 of them, and they may be conjugated or unconjugated. These unsaturated fatty alcohols may be linear or branched. They may optionally comprise in their structure at least one aromatic or non-aromatic ring. They are preferably acyclic. More particularly, the unsaturated liquid fatty alcohols of the 30 invention are chosen from oleyl alcohol, linoleyl alcohol, linolenyl alcohol and undecylenyl alcohol. Oleyl alcohol is most particularly preferred. The term "liquid fatty esters" means an ester derived from a fatty acid and/or from a fatty alcohol that is liquid at standard 18 temperature (25°C) and at atmospheric pressure (760 mmHg, i.e. 1.013 x 105 Pa). The esters are preferably liquid esters of saturated or unsaturated, linear or branched C1-C26 aliphatic monoacids or 5 polyacids and of saturated or unsaturated, linear or branched C1-C26 aliphatic monoalcohols or polyalcohols, the total number of carbon atoms of the esters being greater than or equal to 10. Preferably, for the esters of monoalcohols, at least one of from among the alcohol and the acid from which the esters of the invention 10 are derived is branched. Among the monoesters of monoacids and of monoalcohols, mention may be made of ethyl palmitate, isopropyl palmitate, alkyl myristates such as isopropyl myristate or ethyl myristate, isocetyl stearate, 2-ethylhexyl isononanoate, isodecyl neopentanoate and 15 isostearyl neopentanoate. Esters of C4-C22 dicarboxylic or tricarboxylic acids and of Ci- C22 alcohols and esters of monocarboxylic, dicarboxylic or Iricarboxylic acids and of C4-C26 dihydroxy, trihydroxy, tetrahydroxy or pentahydroxy nonsugar alcohols may also be used. 20 Mention may in particular be made of: diethyl sebacate; diisopropyl sebacate; diisopropyl adipate; di(n-propyl) adipate; dioctyl adipate; diisostearyl adipate; dioctyl maleate; glyceryl undecylenate; octyldodecyl stearoyl stearate; pentaerythrityl monoricinoleate; pentaerythrityl tetraisononanoate; pentaerythrityl tetrapelargonate; 25 pentaerythrityl tetraisostearate; pentaerythrityl tetraoctanoate: propylene glycol dicaprylate; propylene glycol dicaprate; tridecyl erucate; triisopropyl citrate; triisostearyl citrate; glyceryl trilactate; glyceryl trioctanoate; trioctyldodecyl citrate; trioleyl citrate; propylene glycol dioctanoale; neopentyl glycol diheptanoate; 30 diethylene glycol diisononanoate; and polyethylene glycol distearates. Among the esters mentioned above, it is preferred to use ethyl, isopropyl, myristyl, cetyl or stearyl palmitate, 2-ethylhexyl palmitate. 2-octyldecyl palmitate, alley 1 myristates such as isopropyl, butyl, cetyl or 2-octyldodecyl myristate, hexyl stearate, propylene glycol 19 dicaprylate, butyl stearate, isobutyl stearate; dioctyl malate, hexyl laurate, 2-hex.yldecyl laurate, isononyl isononanoate or cetyl octanoate. The composition (A) may also comprise, as liquid fatty ester, 5 sugar esters and diesters of C6-C30 and preferably C12-C22 fatty acids. It is recalled that the term "sugar" means oxygen-bearing hydrocarbon- based compounds containing several alcohol functions, with or without aldehyde or ketone functions, and which comprise at least 4 carbon atoms. These sugars can be monosaccharides, oligosaccharides or 10 polysaccharides. Examples of suitable sugars that may be mentioned include saccharose, glucose, galactose, ribose, fucose, maltose, fructose, mannose, arabinose, xylose and lactose, and derivatives thereof, especially allcyl derivatives, such as methyl derivatives, for instance 15 methylglucose. The sugar esters of fatty acids may be chosen in particular from the group comprising the esters or mixtures of esters of sugars described previously and of linear or branched, saturated or unsaturated C6-C30 and preferably C12-C22 fatty acids. If they are 20 unsaturated, these compounds may comprise one to three conjugated or unconjugated carbon-carbon double bonds, The esters according to this variant may also be chosen from mono-, di-, tri- and tetraesters, and polyesters, and mixtures thereof. These esters may be chosen, for example, from oleates, 25 laurates, palmitates, myristates, behenates, cocoates, stearates, linoleates, linolenates, caprates and arachidonates, or mixtures thereof, such as, in particular, oleopalmitate, oleostearate or palmitostearate mixed esters. More particularly, use is made of monoesters and diesters and 30 in particular of mono- or dioleates, stearates, behenates, oleopalmitates, linoleates, linolenates or oleostearates of sucrose, glucose or methylglucose. 20 An example that may be mentioned is the product sold under the name Glucate® DO by the company Amerchol, which is a methylglucose dioleate. Among the sugar esters, it is also possible to use 5 pentaerythrityl esters, preferably pentaerythrityl tetraisostearate, pentaerythrityl tetraoctanoate, and caprylic and capric acid hexaesters as a mixture with dipentaerythritol. Finally, natural or synthetic esters of mono-, di- or triacids with glycerol may also be used. 10 Among these, mention may be made of plant oils. As oils of plant origin or synthetic triglycerides that may be used in the present invention as liquid fatty esters, examples that may be mentioned include: - triglyceride oils of plant or synthetic origin, such as liquid 15 fatty acid triglycerides containing from 6 to 30 carbon atoms, for instance heptanoic or octanoic acid triglycerides, or alternatively, for example, sesame oil, soybean oil, coffee oil, safflower oil, borage oil, sunflower oil, olive oil, apricot kernel oil, camellia oil, bambara groundnut oil, avocado oil, mango oil, rice bran oil, cottonseed oil, 20 rose oil, kiwi seed oil, seabuckthorn pulp oil, bilberry oil, poppy oil, orange seed oil, sweet almond oil, palm oil, coconut oil, vernonia oil, marjoram oil, baobab oil, rapeseed oil, ximenia oil or pracaxi oil, caprylic/capric acid triglycerides, for instance those sold by the company Stearineries Dubois or those sold under the names Miglyol® 25 810, 812 and 818 by the company Dynamit Nobel, jojoba oil and shea butter oil. Preferably, use will be made, as liquid esters according to the invention, of triglycerides of plant origin, in particular oils chosen from avocado oil, olive oil, camellia oil, apricot kernel oil, and 30 mixtures thereof, and esters of C4-C22 dicarboxylic or tricarboxylic acids and of C1-C22 alcohols, in particular 1,3-propanediol dicaprylate. In order to be considered as a fatty substance, the fatty acid must not be in generally soluble soap form, i.e. it must not be salified with a base. 21 The liquid fatty acids may be chosen from acids of formula RCOOH, in which R is a saturated or unsaturated, linear or branched radical preferably comprising from 7 to 39 carbon atoms. Preferably, R is a C7-C29 alkyl or C7-C29 allcenyl group and 5 better still a C12-C24 alkyl or C12-C24 alkenyl group. R may be substituted with one or more hydroxyl groups and/or one or more carboxyl groups. The liquid fatty acid may in particular be chosen from oleic acid, linoleic acid and isostearic acid. 10 Preferably, the liquid fatty substance(s) is (are) chosen from linear or branched C6-C16 alkanes, fatty alcohols and fatty acid esters, in particular oils of plant origin and esters of C4-C22 dicarboxylic or tricarboxylic acids and of C1-C22 alcohols. The fatty substance(s) used in the composition (A) a according 15 to the invention may also be fatty substances which are non-liquid at ambient temperature (25°C) and at atmospheric pressure (760 mmHg, i.e. 1.013xl05 Pa). The term "non-liquid" preferably means a solid compound or a compound that has a viscosity of greater than 2 Pa.s at a temperature 20 of25°Candatashear rate of 1 s1. More particularly, the non-liquid fatty substances are chosen from fatty alcohols, fatty acid and/or fatty alcohol esters, non-silicone waxes and fatty ethers, which are non-liquid and preferably solid. The non-liquid fatty alcohols suitable for the implementation 25 of the invention are chosen more particularly from saturated or unsaturated and linear or branched alcohols comprising from 8 to 30 carbon atoms. Mention may be made, for example, of cetyl alcohol, stearyl alcohol and a mixture thereof (cetylstearyl alcohol). More particularly, cetylstearyl alcohol will be used. 30 As regards the non-liquid esters of fatty acids and/or of fatty alcohols, mention may be made in particular of solid esters derived from C9-C26 fatty acids and from C9-C26 fatty alcohols. Among these esters, mention may be made of octyldodecyl behenate, isocetyl behenate, cetyl lactate, stearyl octanoate, octyl 22 octanoate, cetyl octanoate, decyl oleate, myristyl stearate, octyl palmitate, octyl pelargonate, octyl stearate, a I ley 1 myristates such as cetyl myristate, myristyl myristate and stearyl myristate, and hexyl stearate. 5 The non-silicone wax(es) are chosen in particular from carnauba wax, candelilla wax, esparto wax, paraffin wax, ozokerite, plant waxes, such as olive tree wax, rice wax, hydrogenated jojoba wax or absolute flower waxes, such as the blackcurrant blossom essential wax sold by Bertin (France), or animal waxes, such as 10 beeswaxes or modified beeswaxes (cerabellina), and ceramides. Solid amides that may be mentioned include ceramides. The ceramides or ceramide analogues, such as glycoceramides, that may be used in the compositions according to the invention are known per se and are natural or synthetic molecules that may correspond to general 15 formula (I) below: R3CHOH — CH— CH2OR2 NH C=0 *< (i) wherein, 20 - Ri denotes a linear or branched, saturated or unsaturated alkyl radical, derived from C14-C30 fatty acids, this radical possibly being substituted with a hydroxyl group in the alpha position or a hydroxyl group in the omega position esterified with a saturated or unsaturated C16-C30 fatty acid; 25 - R2 denotes a hydrogen atom or a (glycosyl)n, (galactosyl)m or sulfogalactosyl radical, in which n is an integer ranging from 1 to 4 and m is an integer ranging from 1 to 8; - I<3 denotes a C15-C26 hydrocarbon-based radical which is saturated or unsaturated in the alpha position, it being possible for this radical to 30 be substituted with one or more C1 -C14 alkyl radicals; 23 it being understood that, in the case of natural ceramides or glycoceramides, R3 may also denote a C15-C26 a-hydroxyalkyl radical, the hydroxyl group being optionally esterified with a C16-C30 a- hydroxy acid. 5 The ceramides which are preferred in the context of the present invention are those described by Downing in Arch. Dermatol., Vol. 123, 1381-1384, 1987, or those described in French patent FR 2 673 179. The ceramide(s) that is (are) more particularly preferred 10 according to the invention is (are) the compound(s) for which Ri denotes a saturated or unsaturated alky 1 derived from C16-C22 fatty acids; R2 denotes a hydrogen atom and R3 denotes a saturated linear C 15 radical. Such compounds are, for example: 15 - N-linoleoyldihydrosphingosine, - N - 01 e 0 y 1 d i h y d r 0 s p h i n g 0 s i n e, -N-palmitoyldihydrosphingosine, - N-steamy Id ihydrosphingosine, -N-behenoyldihydrosphingosine, 20 or mixtures of these compounds. Even more preferentially, use is made of ceramides for which Ri denotes a saturated or unsaturated allcyl radical derived from fatty acids; R2 denotes a galactosyl or sulfogalactosyl radical; and R3 denotes a -CH=CH-(CH2)i2-CH3 group. 25 Other waxes or waxy starting materials that may be used according to the invention are in particular marine waxes such as those sold by the company Sophim under the reference M82, and waxes of polyethylene or of polyolefin in general. The non-liquid fatty ethers are chosen from dialkyl ethers and 30 in particular dicetyl ether and distearyl ether, alone or as a mixture. Preferably, the fatty substance(s) used in the cosmetic composition according to the invention is (are) liquid at ambient temperature and atmospheric pressure. 24 Preferentially, the fatty substance(s) used in the composition (A) according to the invention is (are) chosen from non silicone fatty substance(s), preferably from hydrocarbons, in particular linear or branched C6-C16 alkanes and linear or branched hydrocarbons, of 5 mineral, animal or synthetic origin, with more than 16 carbon atoms, such as liquid parafins, and derivatives thereof, petroleum jelly, liquid petroleum jelly; fatty acid esters, in particular oils of plant origin and esters of C4-C22 dicarboxylic or tricarboxylic acids and of C1-C22 alcohols, these esters being more preferentially chosen from 10 triglycerides of plant origin and liquid fatty alcohols, and mixtures thereof. According to a preferred embodiment, the composition (A) comprises one or more non-silicone fatty substance(s) as described above, preferably liquid at ambient temperature and atmospheric 15 pressure, and more preferentially chosen from petroleum jelly, coconut oil, celylstcaryl alcohol, and mixtures thereof. When the fatty subslance(s) preferably non-silicone fatty substance(s), is (are) present in the composition (A) of the present invention, its (their) total amount ranges from 0.5 to 30% by weight, 20 and preferably from 1 to 15% by weight, relative to the total weight of the composition (A). According to a preferred embodiment, composition (A) is anhydrous, i.e. composition (A) contains less than 5% by weight, preferably less than 2% of water. Preferably composition (A) does not 25 contain water, Composition (B) The term "aqueous composition", according to the present invention, refers to a composition comprising at least 5% by weight of 30 water, relative to the total weight of the composition. Preferably, an aqueous composition comprises more than 10% by weight of water, more preferably more than 20% by weight of water, and better still more than 50% by weight of water, relative to the total weight or the composition. The composition may contain from 5 to 95% by weight, 25 preferably from 10 to 90% by weight and better still from 20 to 80% by weight of water. The aqueous composition (B) according to the present 5 invention comprises one or more direct dye(s),preferably other than the natural plant powder that is present in composition (A). These direct dyes are chosen, for example, from those conventionally used in direct dyeing, and among which mention may 10 be made of any commonly used aromatic and/or non-aromatic dyes such as neutral, acidic or cationic nitrobenzene direct dyes, neutral, acidic or cationic azo direct dyes, natural direct dyes, neutral, acidic or cationic quinone and in particular anthraquinone direct dyes, azine, triarylmethane, indoamine, methine, styryl, porphyrin, 15 metalloporphyrin, phthalocyanine, cyanine and methine direct dyes, and fluorescent dyes. The amount of direct dye(s), present in the composition (B), ranges preferably from 0.001% to 20% by weight, more preferably from 0.005% to 10% by weight, and better still from 0.01 to 5% by 20 weight, relative to the total weight of the composition (B). More preferably, the aqueous composition (B) according to the present invention comprises one or more anionic direct dye(s). 25 Anionic direct dyes The anionic direct dyes of the invention are dyes commonly referred to as "acid" direct dyes for their affinity with alkaline substances. The term "anionic direct dyes" is understood to mean any direct dye comprising, in its structure, at least one CO2R or SO3R 30 subslituent with R denoting a hydrogen atom or a cation originating from a metal or from an amine or an ammonium ion. The anionic dyes can be chosen from acid nitro direct dyes, acid azo dyes, acid azine, acid triarylmethane dyes, acid indoamine dyes, acid anthraquinone dyes, indigoids and acid natural dyes. 26 Mention may be made, as acid dyes according to the invention, of the dyes of following formulae (I), (I'), (II), (IP), (III), (IIP), (IV), (IV), (V), (VI), (VII) and (VIII): a) Diaryl anionic azo dyes of formula (I) or (P) Rg R1Q (I) Rg R1Q (n wherein. ■ R7, Rs, R9, Rio, R'7, R's, R'9 and R'IO, which are identical or different, represent a hydrogen atom or a group chosen from: alkyl; 15 - alkoxy, alkylthio; hydroxyl, mercapto; nitro, nitroso; R°-C(X)-X'-, R°-X'-C(X)-, R°-X'-C(X)-X"-, with R° representing a hydrogen atom or an alkyl or aryl group and X, X' 20 and X", which are identical or different, representing an oxygen or sulphur atom or NR with R representing a hydrogen atom or an alkyl group; (0)2S(0")-M+, with M+ representing a hydrogen atom or a cation ic counter ion; 25 - (0)CO--M+, with M+ as defined above; 27 R"-S(0)2-, with R" representing a hydrogen atom, an alkyl group or an aryl, (di)(alkyl)amino or aryl(alkyl)amino group; preferably a phenylamino or phenyl group; R'"-S(0)2-X'-, with R'" representing an optionally substituted 5 aryl or alkyl group and X' as defined above; (di)(alkyl)amino; aryl(allcyl)amino optionally substituted by one or more groups chosen from i) nitro; ii) nitroso; iii) (0)2S(0~)- M+ and iv) alkoxy with M+ as defined above; 10 - optionally substituted heteroaryl; preferably a benzothiazolyl group; cycloalkyl; in particular cyclohexyl, Ar-N=N-, with Ar representing an optionally substituted aryl group; preferably a phenyl optionally substituted by one or more 15 alkyl, (0)2S(0~)- M'1" or phenylamino groups; or then two adjacent groups R.7 with Rg or Rs with R9 or R9 with Rio together form a fused benzo group A'; and R'7 with R's or R's with R'9 or R'9 with R'10 together form a fused benzo group B'; with A' and B' optionally substituted by one or more groups chosen from 20 i) nitro; ii) nitroso; iii) (0)2S(0")- M+; iv) hydroxyl; v) mercapto; vi) (di)(alkyl)amino; vii) R°-C(X)-X'-; viii) R°-X'-C(X)-; ix) R°-X'- C(X)-X"-; x) Ar-N=N- and xi) optionally substituted aryl(alkyl)amino; with M+, R°, X, X', X" and Ar as defined above;' " W represents a sigma a bond, an oxygen or sulphur atom or a 25 divalent radical i) -NR-, with R as defined above, or ii) methylene - C(Ra)(Rb)-, with Ra and Rb, which are identical or different, representing a hydrogen atom or an aryl group, or then Ra and Rb form, together with the carbon atom which carries them, a spiro cycloalkyl; preferably, W represents a sulphur atom or Ra and Rb together form a 30 cyclohexyl; it being understood that the formulae (I) and (I1) comprise at least one sulphonate radical (0)2S(0~)- M+ or one carboxylate radical (0)CO~-M+ on one of the A, A', B, B' or C rings; preferably sodium sulphonate, 28 Mention may be made, as example of dyes of formula (I), of: Acid Red 1, Acid Red 4, Acid Red 13, Acid Red 14, Acid Red 18, Acid Red 27, Acid Red 28, Acid Red 32, Acid Red 33, Acid Red 35, Acid Red 37, Acid Red 40, Acid Red 41, Acid Red 42, Acid Red 44, Pigment red 57, Acid Red 68, Acid Red 73, Acid Red 135, Acid Red 138, Acid Red 184, Food Red 1, Food Red 13, Acid Orange 6, Acid Orange 7, Acid Orange 10, Acid Orange 19, Acid Orange 20, Acid Orange 24, Yellow 6, Acid Yellow 9, Acid Yellow 36, Acid Yellow 199, Food Yellow 3, Acid Violet 7, Acid Violet 14, Acid Blue 113, Acid Blue 117, Acid Black 1, Acid Brown 4, Acid Brown 20, Acid Black 26, Acid Black 52, Food Black 1, Food Black 2; Food yellow 3 or sunset yellow. And mention may be made, as example of dyes of formula (F), oT: Acid Red 111, Acid Red 134, Acid Yellow 38. b) Pyrazolone anionic azo dyes of formulae (II) and (IF) 16VP'16 / 17 °20 R'2o ^19 •N--Y EVR„ (II') 29 wherein, ■ Rn, R12 and Ri3, which are identical or different, represent a hydrogen or halogen atom or an alky 1 or -(0)2S(0~) M+ group, with M+ as defined above; 5 " R14 represents a hydrogen atom, an alky 1 group or a -C(0)0" M+ group, with M+ as defined above; ■ R15 represents a hydrogen atom: ■ R16 represents an oxo group, in which case R'i6 is absent, or then R1 s with Ri6 together form a double bond; 10 ■ R17 and Ris, which are identical or different, represent a hydrogen atom or a group chosen from: (0)2S(0-)- M + , with MT as defined above; Ar-0-S(0)2-, with Ar representing an optionally substituted aryl group; preferably a phenyl optionally substituted by one or more alkyl 15 groups: ■ R19 and R20 together form either a double bond or an optionally substituted benzo group D'; ■ R'i6, R'19 and R'20, which are identical or different, represent a hydrogen atom or an alkyl or hydroxyl group; 20 ■ R21 represents a hydrogen atom or an alkyl or alkoxy group; ■ Ra and Rb, which are identical or different, are as defined above; preferably, Ra represents a hydrogen atom and Rb represents an aryl group; ■ Y represents either a hydroxyl group or an oxo group; 25 ■ represents a single bond when Y is an oxo group; and represents a double bond when Y represents a hydroxyl group: it being understood that the formulae (II) and (IT) comprise at least one sulphonate radical (0)2S(0~)- M+ or one carboxylate radical -C(0)O M+ on either of the D or E rings; preferably sodium 30 sulphonate. Mention may be made, as example of dyes of formula (II), of: Acid Red 195, Acid Yellow 23, Acid Yellow 27, Acid Yellow 76, and 30 mention may be made, as example of dyes of formula (II1), of: Acid Yellow 17. c) Anthraquinone dyes of formulae (III) and (III') (III) O R„ (HI') 10 wherein, ■ R22, R-23, R-24, R.25, R26 and R27, which are identical or different, represent a hydrogen or halogen atom or a group chosen from: -alkyl; -hydroxyl, mercapto; 1 5 - alkoxy, alkylthio; -optionally substituted aryioxy or arylthio, preferably substituted by one or more groups chosen from allcyl and (0)2S(0")- M+, with M+ as defined above; - aryl(alkyl)amino optionally substituted by one or more groups 20 chosen from alkyl and (0)2S(0")- M+, with M+ as defined above; - (di)(alkyl)amino; 31 - (di) (hydroxy alky 1) ami no; -(0)2S(0-)- M+, with M+ as defined above; ■ Z' represents a hydrogen atom or an NR28R29 group with R28 and R29, which are identical or different, representing a hydrogen atom or 5 a group chosen from: -alkyl; - polyhydroxyalkyl, such as hydroxyethyl; - aryl optionally substituted by one or more groups, particularly i) alkyl, such as methyl, n-dodecyl or n-butyl; ii) (0)2S(0")- M+, with 10 M+ as defined above; iii) R°-C(X)-X'-, R°-X'-C(X)- or R°-X'-C(X)- X"-, with R°, X, X' and X" as defined above; preferably, RD represents an alkyl group; -cycloalkyl; in particular cyclohexyl; ■ Z represents a group chosen from hydroxyl and NR'28R'29 with R'28 15 and R'29, which are identical or different, representing the same atoms or groups as R2S and R29 as defined above; it being understood that the formulae (III) and (III1) comprise at least one sulphonate radical (0)2S(0")- M+ or one carboxylate radical -C(0)0" M + ; preferably sodium sulphonate. 20 Mention may be made, as example of dyes of formula (III), of: Acid Blue 25, Acid Blue 43, Acid Blue 62, Acid Blue 78, Acid Blue 129, Acid Blue 138, Acid Blue 140, Acid Blue 251, Acid Green 25, Acid Green 41, Acid Violet 42, Acid Violet 43, Mordant Red 3; EXT violet N° 2. 25 And mention may be made, as example of dyes of formula (III'), of: Acid Black 48. d)Nitro dyes of formulae (IV) and (IV) 32 (IV) •''"^r^M W—ALK—SO " M1 J u 30'q (R30) NO, (IV) 5 wherein, ■ R30, R31 and R32, which are identical or different, represent a hydrogen or halogen atom or a group chosen from: -alkyl; - allcoxy optionally substituted by one or more hydroxyl groups, 10 alkylthio optionally substituted by one or more hydroxyl groups; -hydroxyl, mercapto; - nitro, nitroso; - polyhaloalkyl; -R°-C(X)-X'-, R°-X'-C(X)- or R°-X'-C(X)-X'"-, with R°, X, X' and 15 X" as defined above; -(0)2S(0")- M+, with M+ as defined above; - (O)CO"- M+, with M+ as defined above; - (di)(alkyl)amino; - (di)(hydroxyalkyl)amino; 20 - heterocycloalkyl, such as piperidino, piperazino or morpholino; particularly, R30, R31 and R32 represent a hydrogen atom; ■ Rc and Rd, which are identical or different, represent a hydrogen atom or an alkyl group; 33 " W is as defined above; W particularly represents an -NH- group; • ALK represents a divalent, linear or branched, C1-C6 allcylene group; particularly, ALK represents a -CH2-CH2- group; 5 ■ n has the value 1 or 2; ■ p represents an integer of between 1 and 5 inclusive; ■ q represents an integer of between 1 and 4 inclusive; ■ u has the value 0 or 1; ■ when n has a value 1, J represents a nitro or nitroso group, 10 particularly a nitro group; ■ when n has a value 2, J represents an oxygen or sulphur atom or a divalent radical -S(0)m- with m representing an integer 1 or 2: preferably, J represents an -SO2- radical; ■ M' represents a hydrogen atom or a cationic counterion; 15 c'X ■ , which is present or absent, represents a benzo group optionally substituted by one or more R30 groups as defined above; it being understood that the formulae (IV) and (IV) comprise at least one sulphonate radical (0)2S(0~)- M+ or one carboxylate radical - 20 C(0)0" M+; preferably sodium sulphonate. Mention may be made, as example of dyes of formula (IV), of: Acid Brown 13; Acid Orange 3; mention may be made, as example of dyes of formula (IV), of: Acid Yellow 1, sodium salt of 2,4-dinitro-1 -naphthol-7-sulphonic acid, 2-piperidino-5-nitrobenzenesulphonic acid, 25 2-(4'-N,N-(2"-hydroxyethyl)amino-2'-nitro)anilineethanesulphonic acid or 4-(P-hydroxyethylamino)-3-nitrobenzenesulphonic acid, EXT D&C yellow 7. 30 e) Triarylmethane dyes of formula (V) 34 "R R R 34 33 R R 41 -N 35 ^37 "^39 v R NM k^k: H R ^^\^^ 4C 38 r^S R 44 ) by weight, and preferably from 1% to 15% by weight relative to the total weight of the composition (A) and/or to 10 the total weight of the aqueous composition (B). The composition (A) and/or the aqueous composition (B) according to the present invention may further comprise one or more additive(s) other than the compounds of the invention, 15 Saccharides According to a preferred embodiment, composition (A) and/or (B), preferably composition (A), of the invention contains one or more optionally reduced saccharides, distinct from the alcohols quoted 20 above as organic solvents. The saccharides may be chosen from monosaccharides, oligosaccharides and polysaccharides. In particular, the saccharides or reduced saccharides of the invention are solid, i.e. they are not liquids or syrups, 25 "Monosaccharides, oligosaccharides and polysaccharides" are known to those skilled in the art (see, for example, Ullmann's Encyclopedia of Industrial Chemistry, published online on 15/04/2010, "CarboJiydrales: Occurrence, Structures and Chemistry", F. W. Lichtenthaler, vol. 6, pp. 617 to 646, DOI: 30 10.1002/143 56007. a05_.079.pub2,). According to a particular embodiment of the invention, the sugar(s) of the dye composition are chosen from monosaccharides, 46 More precisely, the term "monosaccharide" means a sugar comprising only one unit, i.e, not comprising any covalent glycoside bonds with another sugar. Preferentially, the "monosaccharides" of the invention are 5 chosen from: i) "aldoses" or polyhydroxyaldehydes, preferably comprising between 4 and 6 carbon atoms, such as erythrose or threose (4 carbon atoms), ribose, arabinose, xylose or lyxose (5 carbon atoms), allose, altrose, glucose, mannose, gulose, idose, galactose and talose (6 10 carbon atoms); ii) "keloses" or polyhydroxy ketones preferably comprising between 4 and 6 carbon atoms, such as erythrulose (4 carbon atoms), ribulose, or xylulose (5 carbon atoms), psicose, fructose, sorbose and tagatose (6 carbon atoms); and 15 the reduced forms of the aldoses and ketoses as defined previously are also known as "sugar alcohols" or "alditols". They are chosen in particular from erythritol, glucitol or sorbitol, mannitol and xylitol, preferably sorbitol. Sugar alcohols are known to those skilled in the art (see, for 20 example, Ullmann's Encyclopedia of Industrial Chemistry, published online on 15/04/2010, "Carbohydrates: Occurrence, Structures and Chemistry", F. W. Lichtenthaler, vol. 6, chap. 7.6, pp. 637 and 638, DOI: 10.1002/14356007.a05_079.pub2; ibid, published online on 15/01/2012, "Sugar Alcohols", H. Schiweck et al., 2012 Wiley-VCH 25 Verlag GmbH & Co. KGaA, Weinheim, DOI: 10.1 002/143 56007.a25_41 3.pub3 The term "sugar alcohol" means "polyols" generally obtained by reduction of aldose or ketose monosaccharides as defined previously or of complex oligosaccharides or polysaccharides as 30 defined below in which the aldehyde or ketone group(s) of the monosaccharide units are reduced, i.e. replaced with a hydroxyl group. Preferably, the sugars of the invention, and in particular the sugar alcohols according to the invention, are of plant origin, 47 It is understood that the terms "aldoses", "lcetoses" and "sugar alcohols" also refer to the optical isomers thereof, the a and P anomers thereof and the L (laevorotatory) and D (dextrorotatory) forms thereof. More preferentially, the monosaccharides of the invention 5 comprise 6 carbon atoms. The term "oligosaccharide" means a sugar in which the monosaccharides as defined previously are combined together via a covalent glycoside bond to give a simple polymer comprising from 2 to 10 monosaccharide units. 10 In particular, the oligosaccharides are chosen from disaccharides such as sucrose, trehalose and raffinose, lactose, cellobiose and maltose; a, P or y-cyclodextrins and the "sugar alcohol" reduced forms thereof such as isomaltulose, trehalulose, isomalt, maltitol and lactitol. 15 It is understood that the term "oligosaccharides" also refers to the optical isomers thereof, the a and P anomers thereof and the L (laevorotatory) and D (dextrorotatory) forms thereof. The term "polysaccharides" means oligosaccharides which comprise at least 11 monosaccharide units. Preferentially, the 20 polysaccharides of the invention comprise between 20 and 100 000 monosaccharide units. The polysaccharides of the invention may be chosen from those derived from the following sugars: i) glucose; ii) galactose; iii) arabinose; iv) rhamnose; v) mannose; vi) xylose; vii) fucose; viii) 25 anhydrogalactose; ix) galacturonic acid; x) glucuronic acid; xi) mannuronic acid; xii) galactose sulfate; xiii) anhydrogalactose sulfate. The polymers bearing sugar units of the invention may be natural or synthetic. They may be nonionic, anionic, amphoteric or cationic. 30 According to a particular mode of the invention, the saccharide(s) of the invention are other than sucrose. According to a particularly advantageous mode of the invention, the saccharide(s) of the invention are chosen from monosaccharides and disaccharides and in particular from aldoses, 48 ketoses and the reduced forms thereof, namely sugar alcohols such as sorbitol. Preferentially, sugar(s) are chosen from sugar alcohols of aldose and ketose monosaccharides such as sorbitol, According to a particular embodiment of the invention, 5 composition A contains at least a saccharide, as above described, preferably chosen from monosaccharides in reduced form, especially sugar alcohols such as sorbitol. According to a particular embodiment of the invention, the saccharide(s) are in an amount inclusively between 0.1% and 30% by 10 weight, relative to the total weight of composition ' A, more particularly between 0.2% and 20% by weight, preferentially between 0.5% and 10% by weight and more preferentially between 0.7% and 5% by weight relative to the total weight of the said composition. As other additives that may be used in accordance with the 15 invention, mention may be made of cationic, anionic, nonionic or amphoteric polymers or mixtures thereof, cationic, anionic, non-ionic, zwitterionic or amphoteric surfactants or mixtures thereof antidandruff agents, anti-seborrhoea agents, agents for preventing hair loss and/or for promoting hair regrowth, sunscreens, mineral or organic pigments, 20 sequestrants, plasticizers, solubilizers, acidifying agents, mineral or organic thickeners, especially polymeric thickeners, opacifiers or nacreous agents, antioxidants, fragrances and preserving agents. Needless to say, a person skilled in the art will take care to select this or these optional additional compound(s) such that the 25 advantageous properties intrinsically associated with the composition according to the invention are not, or are not substantially, adversely affected by the envisaged addition(s). The above additives may generally be present in an amount, for each of ihcm, of between 0.001% and 20% by weight relative to the 30 total weight of the composition (A) and/or to the total weight of the aqueous composition (B). Additives 49 The composition (A) and/or the aqueous composition (B) according to the present invention may further comprise one or more additive(s) other than the compounds of the invention. As additives that may be used in accordance with the invention, 5 mention may be made of anionic, nonionic or amphoteric polymers. different from polysaccharides previously described, or mixtures thereof, antidandruff agents, anti-seborrhoea agents, agents for preventing hair loss and/or for promoting hair regrowth, sunscreens, mineral or organic pigments, sequestrants, plasticizers, solubilizers, , 10 mineral or organic thickeners, especially polymeric thickeners different from polysaccharides previously described, opacifiers or nacreous agents, antioxidants, fragrances and preserving agents. Needless to say, a person skilled in the art will take care to select this or these optional additional compound(s) such that the 15 advantageous properties intrinsically associated with the composition according to the invention are not, or are not substantially, adversely affected by the envisaged addition(s). The above additives may generally be present in an amount, for each of them, of between 0.001% and 20% by weight relative to the 20 total weight of the composition (A) and/or to the total weight of the aqueous composition (B), Method for dyeing keratin fibres 25 Another object of the present invention relates to a method for dyeing keratin fibres, and in particular human keratin fibres, wherein the following steps are successively performed: - applying a sustained pressure to the closed envelop 2 in the region of at least one compartment 7a or 7b of the multiple- 30 compartment device 1, in order to break the internal frangible seal 8, - opening the closed envelop 2 of said multiple-compartment device, and - applying the mixture of compositions (A) and (B), as previously defined, on said keratin fibres. 50 Preferably, the sustained pressure is applied to the compartment 7b comprising the aqueous composition (B) in order to break the internal frangible seal 8. After breaking the internal frangible seal 8, compositions (A) 5 and (B) commingle instantly in order to provide a dyeing composition. The dyeing composition may be mixed by shaking or turning upside-down the closed envelop 2. The closed envelop 2 is then opened by way of tearing or cutting with a pair of scissors. 10 According to a preferred embodiment, the closed envelop 2 is opened by tearing the pre-cut line 14. The dyeing composition thus obtained is then directly applied on the keratin fibres. After an optional leave-on time, the dyeing composition is 15 rinsed with water. In the present invention, the term "keratin fibres" denotes human keratin fibres, and in particular human hair. The examples that follow serve to illustrate the invention without, however, being limiting in nature. 51 EXAMPLES In the examples that follow and unless otherwise indicated, all the amounts are given as mass percentages of active material relative 5 to the total weight of the composition. 1. Compositions The following compositions (A) and (B) can be prepared according to the following ingredients shown in the table below, the 10 amounts of which are expressed as percent by weight, with respect to the total weight of the composition. Composition (A) Coconut oil 10 Sorbitol 1 Lawsonia inermis leaf powder 88.34 Fragrance 0.6 Vitamin B3 (Niacinamide) 0.01 Vitamine E: DL-alpha-tocopherol 0.05 15 Aqueous composition (B) . - . . . Disodium salt of tartrazine (Yellow 5; CI 19140) 0.67 Sodium salt of orange 2 (Orange 4; CI 155 10) 0.67 Sodium salt of alizurol purple (EXT Violet 2; CI 60730) 0.45 Benzyl alcohol 13.33 Citric acid 8 Acid black 1 (CI 20470) 0.67 Water Qs 100 The compositions can be introduced into a dual sachet made of a multilayer polyethylene film and divided into two iso-size compartments separated by a frangible seal. Composition A can be introduced in one compartment and composition B in the second compartment so that both compositions are not in contact during the time of storage. The ratio between composition A and composition B can range from 0.5:99.5 to 99.5:0.5, in particular about 25:75. At the time of use, a hand-pressure can be applied onto the compartment containing composition B, enabling to break the seal in-between and allowing both compositions to easily mix together. The mixture thereof can then be kept soaking for 15 minutes. The composition according to the invention is expected to provide an instant composition that confers good dyeing properties to the hair, especially significant darker and more intense colouration, especially significant dark and intense colouration . WE CLAIM 1.Multiple-compartment device (1) composed of a closed envelop (2), made of at least two flexible sidewalls (3a, 3b) secured together along their peripheral edges (4), defining a sealed perimeter (5) and an internal volume (6); said internal volume (6) being divided in at least two distinct compartments (7a) and (7b), separated from one another by at least one internal frangible seal 8, wherein at least one of the compartments (7a) contains a composition (A), comprising at least one natural plant powder and the second compartment (7b) contains an aqueous composition (B) comprising at least one direct dye . 2. Multiple-compartment device (1) according to the preceding claim, wherein the closed envelop (2) is made of at least one sheet of polymeric film folded back on itself and sealed at its peripheral edges. 3. Multiple-compartment device (1) according to claim 2. wherein the sheet of polymeric film is a multilayer polymeric film comprising at least two, different or identical, layers of polymeric film. 4. Multiple-compartment device (1) according to any one of claims 2 and 3, wherein the sheet of polymeric film is prepared from polyvinyl chloride, polyesters, polyolefins, polyamides or polystyrenes. 5. Multiple-compartment device (1) according to any one of the preceding claims, wherein it further comprises an opening means, preferably a pre-cut line (14) parallel to a first end (9) of the sealed perimeter (5). 6. Multiple-compartment device (1) according to any one of the preceding claims, wherein a second end (10) of the sealed perimeter (5) has a bottom (15) and involves a folded gusset structure (16). 7. Multiple-compartment device (1) according to any one of the preceding claims, wherein the natural plant powder is chosen from henna plant powder, indigo plant powder or mixtures thereof 8. Multiple-compartment device (1) according to any one of the preceding claims, wherein the natural plant powder is chosen from red henna powder of Lawsonia, Indigofera linctoria, and mixtures thereof 9. Multiple-compartment device (1) according to any one of the preceding claims, wherein the amount of plant powder is greater than or equal to 50% by weight, preferably greater than or equal to 60% by weight, and more preferably greater than or equal to 70% by weight, relative to total weight of the composition (A). 10. Multiple-compartment device (1) according to any one of the preceding claims, wherein the composition (A) further comprises one or more fatty substance(s), preferably one or more non- silicone fatty substance(s), preferably liquid at ambient temperature and atmospheric pressure. I 1 . Multiple-compartment device (1) according to claim 10, wherein the fatty substances are chosen from hydrocarbons, in particular linear or branched C6-C[6 alkanes and linear or branched hydrocarbons, of mineral, animal or synthetic origin, with more than 16 carbon atoms, such as liquid parafins, and derivatives thereof, petroleum jelly, liquid petroleum jelly; fatty acid esters, in particular oils of plant origin and esters of C-1-C22 dicarboxylic or tricarboxylic acids and of C1-C22 alcohols, these esters being more preferentially chosen from triglycerides of plant origin and liquid fatty alcohols, and mixtures thereof. 12. Multiple-compartment device (1) according to any one of claims 10 and 11, wherein the amount of fatty substances, preferably non-silicone fatty substance(s), is greater than or equal to 5% by weight, preferably greater than or equal to 7% by weight, and better still greater than or equal to 10% by weight, relative to the total weight of the composition (A). 13. Multiple-compartment device (1) according to any one of the preceding claims, comprising at least one anionic direct dye . 14. Multiple-compartment device (1) according to the preceding claim, wherein the anionic direct dyes are chosen from: a) Diaryl anionic azo dyes of formula (I) or (I') R„ R 10 (I) R9 R10 (I') wherein, R7, Rs, R9, Rio, R'7, R's, R'9 and R'IO, which are identical or different, represent a hydrogen atom or a group chosen from: alkyl; alkoxy, alkylthio; hydroxyl, mercapto; nitro, nitroso; R°-C(X)-X'-, R°-X'-C(X)-, R°-X'-C(X)-X"-, with R° representing a hydrogen atom or an alkyl or aryl group and X, X' and X", which are identical or different, representing an oxygen or sulphur atom or NR with R representing a hydrogen atom or an alkyl group; (0)2S(0-)- M + , with M+ representing a hydrogen atom or a cationic counterion; (O)CO'- M+, with M+ as defined above; R"-S(0)2-, with R" representing a hydrogen atom, an alkyl group or an aryl, (di)(alkyl)amino or aryl(alkyl)amino group; R"'-S(0)2-X'-, with R'" representing an optionally substituted aryl or alkyl group and X' as defined above; (d i) (a I k y I) a m i n o; aryl(alkyl)amino optionally substituted by one or more groups chosen from i) nitro; ii) nitroso; iii) (0)2S(0-)- M+ and iv) alkoxy with M+ as defined above; optionally substituted heteroaryl; preferably a benzothiazolyl group; cycloalkyl; in particular cyclohexyl, Ar-N=N-, with Ar representing an optionally substituted aryl group; or then two adjacent groups R7 with Rg or Rg with R9 or R9 with Rio together form a fused benzo group A1; and R'7 with R'g or R's with R'9 or R'9 with R'IO together form a fused benzo group B'; with A' and B' optionally substituted by one or more groups chosen from i) nitro; ii) nitroso; iii) (0)2S(0")- M+; iv) hydroxyl; v) mercapto; vi) (di)(alkyl)amino; vii) R°-C(X)-X'-; viii) R°-X'-C(X)-; ix) R°-X'- C(X)-X"-; x) Ar-N=N- and xi) optionally substituted aryl(alkyl)am ino; with M + , R°, X, X', X" and Ar as defined above: ■ W represents a sigma a bond, an oxygen or sulphur atom or a divalent radical i) -NR-, with R as defined above, or ii) methylene - C(Ra)(Rb)-, with Ra and Rb, which are identical or different, representing a hydrogen atom or an aryl group, or then Ra and Rb form, together with the carbon atom which carries them, a spiro cycloalkyl; it being understood that the formulae (I) and (I1) comprise at least one sulphonate radical (0)2S(0-)- M+ or one carboxylate radical (0)CO~- M+ on one of the A, A1, B, B1 or C rings; preferably sodium sulphonate: b) Pyrazolone anionic azo dyes of formulae (II) and (II1) ■N R2o R'20 R19 R16*R'l6 /R17 (IT') wherein, * Rn, R12 and R13, which are identical or different, represent a hydrogen or halogen atom or an alkyl or -(0)2S(0") M+ group, with M + as defined above; " Ri4 represents a hydrogen atom, an alkyl group or a -C(0)0" M + group, with MH as defined above; ■ R15 represents a hydrogen atom; ■ Ri6 represents an oxo group, in which case R'i6 is absent, or then R15 with Ri6 together form a double bond; * R[7 and Ris, which are identical or different, represent a hydrogen atom or a group chosen from: (0)2S(Cr)- M+, with M+ as defined above; Ar-0-S(0)2-, with Ar representing an optionally substituted aryl group; " R19 and R20 together form either a double bond or an optionally substituted benzo group D'; ■ R'16, R'IQ and R'20, which are identical or different, represent a hydrogen atom or an alky] or hydroxyl group; ■ R21 represents a hydrogen atom or an alky 1 or alkoxy group; ■ Ra and Rb, which are identical or different, are as defined above; ■ Y represents either a hydroxyl group or an oxo group; ■ represents a single bond when Y is an oxo group; and represents a double bond when Y represents a hydroxyl group; it being understood that the formulae (II) and (IT) comprise at least one sulphonate radical (0)2S(0~)- M+ or one carboxylate radical -C(0)0" Mf on either of the D or E rings; preferably sodium sulphonate; c) Anthraquinone dyes of formulae (III) and (III') (III) (III') wherein, ■ R.22, R23, R24, R-2S, R26 and R27, which are identical or different, represent a hydrogen or halogen atom or a group chosen from: -alkyl; -hydroxyl, mercapto; - alkoxy, alkylthio; -optionally substituted aryloxy or arylthio; - aryl(alkyl)amino optionally substituted by one or more groups chosen from alkyl and (0)2S(0")- M+, with M+ as defined above; - (di)(alkyl)amino; - (di)(hydroxyalkyl)amino; -(0)2S(0-)- M+, with M+ as defined above; " Z' represents a hydrogen atom or an NR28R29 group with R2s and R29, which arc identical or different, representing a hydrogen atom or a group chosen from: -alkyl; - polyhydroxyalkyl, such as hydroxyethyl; -aryl optionally substituted by one or more groups, particularly i) alkyl, such as methyl, n-dodecyl or n-butyl; ii) (0)2S(0")- M+, with VT as defined above; iii) R°-C(X)-X'-, R°-X'-C(X)- or R°-X'-C(X)-X"-, with R°, X, X' and X" as defined above; -cycloalkyl; in particular cyclohcxyl; ■ Z represents a group chosen from hydroxyl and NR'2sR'29 with R'28 and R'29, which are identical or different, representing the same atoms or groups as R2S and R29 as defined above; it being understood that the formulae (III) and (III1) comprise at least one sulphonate radical (0)2S(0")- M+ or one carboxylate radical -C(0)0~ M+; preferably sodium sulphonate; d) Nitro dyes of formulae (IV) and (IV) 02N M' SO Rc R31 Rd R 32 (IV) 30'q (RM) r^M NO, W—ALK—SO ' M' J u (IV) wherein, " R30, R31 and R32, which are identical or different, represent a hydrogen or halogen atom or a group chosen from: -alkyl; -aikoxy optionally substituted by one or more hydroxyl groups, alkylthio optionally substituted by one or more hydroxyl groups; -hydroxyl, mercapto; - nitro, nitroso; - polyhaloalkyl; -R°-C(X)-X'-, R°-X'-C(X)- or R°-X,-C(X)-X'"-, with R°, X, X' and X" as defined above; -(0)2S(0-)- M+, with M+ as defined above; - (O)CO-- M + , with M+ as defined above; - (di)(alkyl)amino; - (di)(hydroxyalkyl)amino; - heterocycloalkyl, such as piperidino, piperazino or morpholino; ■ Rc and Rd, which are identical or different, represent a hydrogen atom or an alkyl group; » W is as defined above; W particularly represents an -NH- group; ■ ALK represents a divalent, linear or branched, Ci-Cg alkylene group; particularly, ALK represents a -CH2-CH2- group; ■ n has the value 1 or 2; ■ p represents an integer of between 1 and 5 inclusive: ■ q represents an integer of between 1 and 4 inclusive; ■ u has the value 0 or 1; ■ when n has a value 1, J represents a nitro or nitroso group, particularly a nitro group; » when n has a value 2, J represents an oxygen or sulphur atom or a divalent radical -S(0)m- with m representing an integer 1 or 2; ■ M' represents a hydrogen atom or a cationic counterion; , which is present or absent, represents a benzo group optionally substituted by one or more R30 groups as defined above; it being understood that the formulae (IV) and (IV) comprise at least one sulphonate radical (0)2S(0~)- M'1 or one carboxylate radical -C(0)0" MH; preferably sodium sulphonate; e) Triarylmethane dyes of formula (V) "R R 34 33 R -N 35 °37 39> R >^v ,WN: 43 R« R 36 (V) wherein, ■ R.33, R31, R35 and R36, which are identical or different, represent a hydrogen atom or a group chosen from alkyl, optionally substituted aryl and optionally substituted arylalkyl; ■ R37, R-38, R39, R40, R41, R42, R43 and R44, which are identical or different, represent a hydrogen atom or a group chosen from: -alkyl; - alkoxy, alkylthio; - (di)(alkyl)amino; - hydroxyl, mercapto; - nitro, nitroso; -R°-C(X)-X'-, R°-X'-C(X)- or R°-X'-C(X)-X"-, with R° representing a hydrogen atom or an alkyl or aryl group and X, X' and X", which are identical or different, representing an oxygen or sulphur atom or NR, with R representing a hydrogen atom or an alkyl group; -(0)2S(0")- M'", with M+ representing a hydrogen atom or a cationic counterion; - (O)CO'- M+, with M+ as defined above; -or then two adjacent groups R41 with R42 or R42 with R43 or R43 with R44 together form a fused benzo group: I'; with I' optionally substituted by one or more groups chosen from i) nitro; ii) nitroso; iii) (0)2S(0")- M+; iv) hydroxyl; v) mercapto; vi) (di)(alkyl)amino; vii) R°-C(X)-X'-; viii) R°-X'-C(X)-; ix) R0-X'-C(X)-X"-; with M+, R°, X, X' and X" as defined above; it being understood that at least one of the G, H, I or I' rings comprises at least one sulphonate radical (0)2S(0~)- or one carboxylate radical -C(0)0~; preferably sulphonate; f) Dyes derived from xanthene of formula (VI) wherein, " R45, R46, R47 and R.4 8, which are identical or different, represent a hydrogen atom or a halogen atom; ■ R49, R50, Rsi and R52, which are identical or different, represent a hydrogen or halogen atom or a group chosen from: -alkyl; - alkoxy, alkylthio; -hydroxyl, mercapto; - nitro, nitroso; -(0)2S(0~)- M + , with M"1" representing a hydrogen atom or a cationic counterion; -(O)CO-- M + , with M1' as defined above; ■ G represents an oxygen or sulphur atom or an NRe group with Re as defined above; " L represents an alkoxide O" M+; a thioalcoholate S" M+ or an NRr group, with RF representing a hydrogen atom or an alkyl group, and M"1 as defined above; ■ L' represents an oxygen or sulphur atom or an ammonium group: N + RrRg, with Rf and Rg, which are identical or different, representing a hydrogen atom or an optionally substituted aryl or alkyl group; ■ Q and Q', which are identical or different, represent an oxygen or sulphur atom; • M1 is as defined above; g) Dyes derived from indole of formula (VII) (VII) wherein, ■ R53, R54, Rss, R56, R57, R58, R59 and R60, which are identical or different, represent a hydrogen atom or a group chosen from: -alkyl; - alkoxy, alkylthio; -hydroxy), mercapto; - nitro, nitroso; -R°-C(X)-X'-S R°-X'-C(X)- or R°-X'-C(X)-X"-, with R° representing a hydrogen atom or an alkyl or aryl group and X, X' and X", which are identical or different, representing an oxygen or sulphur atom or NR, with R representing a hydrogen atom or an alkyl group; -(0)2S(0~)- Mh, with M"1 representing a hydrogen atom or a cationic counlerion; -(O)CO-- M+, with M+ as defined above; " G represents an oxygen or sulphur atom or an NRe group with Re as defined above; ■ Ri and Rh, which are identical or different, represent a hydrogen atom or an alkyl group; it being understood that the formula (VII) comprises at least one sulphonate radical (0)2S(0")- M'" or one carboxylate radical -C(0)0~ M + ; preferably sodium sulphonate; h) Dyes derived from quinoline of formula (VIII) (VIII) wherein, ■ Rfii represents a hydrogen or halogen atom or an alky 1 group; ■ R.62, R63 and R64, which are identical or different, represent a hydrogen atom or an (0)2S(0-)- M+ group, with M+ representing a hydrogen atom or a cationic counterion; ■ or then R6i with R62 or R.61 with R64 together form a benzo group optionally substituted by one or more (0)2S(0")- M"1" groups, with M+ representing a hydrogen atom or a cationic counterion: it being understood that the formula (VIII) comprises at least one sulphonate radical (0)2S(0-)- M+, preferably sodium sulphonate; i) the mcsomeric or tautomeric forms of the structures (I) to (VIII); j) and mixtures thereof. 15. Multiple-compartment device (1) according to any one of the preceding claims, wherein the composition (A) and/or (B), preferably the composition (A) further comprises at least one saccharide, chosen from monosaccharides and disaccharides and in particular from aldoses, ketoses and the reduced forms thereof, namely sugar alcohols such as sorbitol, 16. Multiple-compartment device (1) according to any one of the preceding claims, wherein the saccharide(s) are in an amount inclusively between 0.1% and 30% by weight, more particularly between 0.2% and 20% by weight, preferentially between 0.5% and 10% by weight and more preferentially between 0.7% and 5% by weight relative to the total weight of the composition (A) and/or (B). 17. Multiple-compartment device (1) according to any one of the preceding claims, wherein the aqueous composition (B) further comprises one or more organic acid(s). 18. Multiple-compartment device (1) according to any one of the preceding claims, wherein the composition (A) and/or (B), preferably the composition (B) comprises at least one organic solvent, preferably chosen from aromatic alcohols or ethers, particularly benzyl alcohol. 19. Multiple-compartment device (1) according to claim 17, wherein the amount of organic solvents ranges from 0.5% to 25% by weight, and preferably from 1% to 15% by weight relative to the total weight of the composition (A) and/or to the total weight of the aqueous composition (B). 20. Method for dyeing keratin fibres, and in particular human keratin fibres, wherein the following steps are successively performed: - applying a sustained pressure to the closed envelop (2) in a region of at least one compartment (7a, 7b) of a multiple-compartment device (1) as defined in any one of the preceding claims, in order to break the internal frangible seal (8), - opening the closed envelop (2) of said multiple-compartment device (1), and - applying the mixture of compositions (A) and (B), as defined in any one of the preceding claims, on said keratin fibres.