42 ANATOMY AND PHYSIOLOGY OF 



Zygnema,SsjG,, and of the chlorophyll globules consists of the green 

 colouring matter ; so that in pieces of plants from^ which the 

 colour has been extracted by alcohol, they are found little altered 

 in size, as softish masses which are coloured yellow by iodine, 

 therefore contain nitrogen. Whether tliis is simply albumen, as 

 Treviranus states, remains to be proved ; but it is probable that it 

 is a proteine compound 



Even in the matter extracted by ether, the true green colouring 

 substance forms but an extremely small portion, according to 

 Mulder's researches (''Physiological Ghemistry,'' 275), since the 

 great mass of that which is soluble in efcher consists of wax. The 

 chemical composition of chlorophyll is not yet made out with cer- 

 tainty ; Mulder's analysis gave Cis His N2 O3, but requires repeti- 

 tion. From his researches it would appear that chlorophyll is 

 allied to the indigo-like bodies, and Mulder considers it probable 

 that uncoloured chlorophyll exists in all parts of the plant, 

 capable of conversion into green by free oxygen ; a conjecture, 

 however, against which speaks the circumstance that neither the 

 expressed sap, nor any tissue whatever of plants, acquires a green 

 colour by exposure to the influence of the air. 



Starch granules are very frequently enclosed in the chlorophyll 

 granules. (See " On the AnatoTnieal Condition of Ghlorophyll/' 

 in my " Vermischte Schrift.") and not only in the band-shaped 

 strips of Zygnema, but in an extraordinary number of cases in 

 the chlorophyll granules of the most varied plants, and especially 

 distinctly in those of Ghara, Sometimes only one starch granule 

 exists in the chlorophyll grain, sometimes sevei'al, but usually not 

 more than three or four ; in Anthoceros alone I found from 50 to 

 100 starch granules in each of them. These starch granules are 

 usually of very small size ; the longest I determined at l~300th of 

 a line, the smallest, acquiring a distinct blue colour with iodine, 

 l-2000th of a line, and it still remains uncertain whether or not 

 still smaller granules, which occur in many cases in chlorophyll, 

 consist also of starch. The history of the development of chloro- 

 phyll is still involved in obscurity. So far as I have traced the 

 matter, it stands in the closest connexion with protoplasm at its 

 jBirst appearance in uncoloured organs which have been developed 

 in the dark, when the formation of chlorophyll is brought about 

 in these by the influence of light ; for on the first appearance of 

 the green colour, isolated portions of the protoplasm are seen to 

 assume a greenish tint, exhibiting the form of granular patches of 

 mucilage having no definite outline. Subsequently, the starch 

 granules, where such occur in the cells, e. g^^ in the potato, or any 

 young leaves, become clothed by a more or less thick coat of 

 chlorophyll presenting a distinct boundary line ; wHle in other 

 cells chlorophyll granules are met with which contain no starch. 

 In other cases in which the very young organs contain no starch, 

 6. </., in the vegetating points of Gonferua glomerata, granules of 



