4b MORPHOLOGY OF THE CELL. 



body of the cell itself contains, in addition to the green colouring matter, a red, 

 blue, or yellow substance soluble in water ; the fresh chlorophyll-body appears then, 

 by the admixture of the chlorophyll contained in it with these substances, verdigris- 

 green (Oscillatoria, Peltigera canina, &c. ), a fine red (Florideae), or brown (Fucus, 

 Laminaria saccharina), or buff (Diatomacese). (Cf. Book II. Algae). 



From this are to be distinguished those processes in which the originally green 

 chlorophyll grains assume a red or yellow colour from transformation of their 

 colouring material ; these, in reference to their physiological bearings, I have 

 designated a degradation of chlorophyll. Thus the green bodies in the walls of 

 the antheridia of Mosses and Characeae become, at the time of fertilisation, of a 

 beautiful red; in ripening fruits {Lycium barbanwi, Solanwn pseiido-capsicwn, &c.), 

 the change of colour from green to yellow and red depends also on a similar 

 loss of colour of the chlorophyll-grains, accompanied by a breaking up into angular 

 forms with two or three points (Kraus, /. c). Nearly related to the grains of 

 chlorophyll are the vehicles of the yellow colouring materials to which many 

 petals owe their yellow colouring {e.g. Cucurbita). The occasional blue {Tilland- 

 sia amcetia) or brown and violet {Orchis Mon'o) bodies, are much further removed 

 from this type, although they also have a basis similar to protoplasm which is 

 tinged by a colouring material, in these cases soluble in water. 



(a) The Substance of the Chlorophyll-bodies is, irrespectively of the contents re- 

 ferred to, destitute of those fine granules which are so generally distributed through 

 colourless motile protoplasm ; in spite of their sharply defined form, they are very 

 soft, and greasy M'hen crushed ; when they come into contact with pure water, vacuoli 

 are formed, which at last, from their great distension, burst through the green substance 

 as hyaline bladders ; young grains of chlorophyll may thus become converted into delicate 

 bladders, in which the grains of starch remain ; old grains have a greater consistence. 

 After extraction of the green colouring matter out of true chlorophyll-bodies, e.g. the 

 bands of Spirogyra or grains of Allium Cepa, the remaining colourless ground-substance 

 possesses greater power of resistance, is coagulated, and shows all the reactions of proto- 

 plasm already mentioned. 



(b) The Origin of the Chlorophyll-bodies has, at present, only been directly observed 

 in the granular forms; it can to some extent be compared with the process of free 

 cell-formation; around given centres of formation within the protoplasm extremely 

 small portions of it collect, forming sharply defined masses ; if the centres of forma- 

 tion are at a considerable distance from one another, the chlorophyll-grains become 

 round (as in hairs of Cucurbita) ; but if they lie close to one another and the grains 

 are large, they are at first polygonal, as if they had been flattened against one 

 another by pressure. The process then gives somewhat the same impression as the 

 formation of numerous small zoospores in a sporangium of Achlya (Fig. 9, A) ; only 

 that in this latter case colourless protoplasm always continues to lie between the green 

 portion (parietal chlorophyll-grains of the leaves of Phanerogams). If a mass of pro- 

 toplasm collects around the central nucleus during the formation of chlorophyll, the 

 grains are often formed in its neighbourhood ; they may then revolve with the circu- 

 lating protoplasm in the cell, or afterwards assume definite positions. In the filamentous 

 Algae with apical growth {e. g. Vaucheria, Bryopsis), they form in the colourless 

 protoplasm-body of the growing end of the sac, and then remain applied to the wall. 

 In ripe spores of Osmunda regalis the chlorophyll surrounds the nucleus in the form of 

 amorphous cloudy masses, which, however, separate on germination as oval grains, at 

 first weakly afterwards sharply defined (Kny). In the chlorophyll-forming cells of 

 the embryo-leaves of Phanerogams (cotyledons of the sunflower, primordial leaves of 



