180 NATURAL SCIENCE [September 



that colourless protoplasm is quite competent to effect the dissocia- 

 tion in question (i.e. if such ever actually does come to pass), pro- 

 vided always that its forces are sufficiently concentrated and its 

 position favourable. It is known that the protoplasm of the chloro- 

 phyll bodies is, like that of the nucleus, denser than the cytoplasm, 

 and this increase of density is doubtless associated with an aug- 

 mentation of vital energy and activity. Then why may not the 

 nucleus with all its superior density likewise achieve the decomposi- 

 tion of carbon dioxide ? Because its composition is utterly different 

 from that of the cytoplasm ; its function is to generate not special 

 matters, but special motions ; it excites the activity of the cytoplasm, 

 but is not indispensable for metabolism ; it is no part of its business to 

 decompose gases or liquids ; in fact, according to Preyer and Windt, 

 it merely regulates the progress of the assimilation and de-assimila- 

 tion of the protoplasm. In this connection it may suffice to merely 

 mention the amyloplasts of Schimper, the leucoplasts of Sachs, and 

 the free formation of starch without the intervention of chlorophyll, 

 or even of leucites demonstrated by Belzung. 



If we profoundly consider the matters herein and just now set 

 forth, we can hardly resist the conclusion that chlorophyll, i.e. 

 the simple pigmentary substance, is not truly the cause or indis- 

 pensable auxiliary of the assimilative energy of the protoplasm of 

 the leaf, but rather it is one of the direct and immediate conse- 

 quences of the vital activity thereof. Whatever increases and 

 heightens the vital activity increases at the same time and pari 

 passu the amount of chlorophyll. The peculiar and characteristic 

 feature in connection therewith is that it is not really a waste- 

 product, or an excretion in any sense, or a product of de-assimilation ; 

 it is a specific consequence of the specific life activity interwoven 

 with a protoplasmic substratum, whose molecules dissociate but do 

 not degrade. Living protoplasm has an active power of respiration, 

 and the greening of etiolated leaves grown in the dark is, when they 

 are exposed to light, for and by itself no assimilation process, and it 

 takes place without decomposition of carbon dioxide. The pigment 

 itself is almost certainly a dark dull blue substance, such as can be iso- 

 lated from C4ramineae more especially, and the mixture thereof with the 

 brilliant and stable yellow carotin, which all leaves contain, affords the 

 greenery, and at the same time vivifies and, as it were, burnishes it. 



If Mr Etard's conclusions that a given species of plant may 

 contain several kinds of chlorophyll be provisionally accepted, it is 

 indispensable that the term ' chlorophyll ' should mean not the pure 

 pigment only, but the entire waste or excretion ensuing from the 

 chemical processes undergone in the protoplasm of the chloroplastids. 

 His researches furnish a twofold basis. " It is the chlorophylls," he 

 states, " that are insoluble in pentane, which tend on splitting up to 



