474 BOTANICAL WORK OF THE BRITISH ASSOCIATION. 



by the oxidation of ammonia. This brings us down to the fact, which 

 has long been suspected, that protoplasm is at the bottom of the whole 

 business, and that chlorophyll only plays some subsidiary and indirect 

 part, perhaps, as Adolph Baeyer long ago suggested, of temporarily 

 fixing carbon oxide like hemoglobin, and so facilitating the dissociation. 



Chlorophyll itself is still the subject of careful study by Dr. Schunck, 

 originally commenced by him some years ago at Kew. This will, I hope, 

 give us eventually an accurate insight into the chemical constitution 

 of this important substance. 



The steps in plant metabolism which follow the synthesis of the 

 protocarbohydrate are still obscure. Brown and Morris have arrived 

 at the unexpected conclusion that "cane sugar is the first sugar to be 

 synthesized by the assimilatory processes." I made some remarks 

 upon this at the time (Journ. Chem. Soc, 1893, 673), which I may be 

 permitted to reproduce here : 



"The point of view arrived at by botanists was briefly stated by 

 Sachs in the case of the sugar beet, starch in the leaf, glucose in the 

 petiole, cane sugar in the root. The facts in the sugar cane seem to be 

 strictly comparable. (Kew Bulletin, 1891, 35-41.) Cane sugar the bota- 

 nist looks on, therefore, as a 'reserve material.' We may call 'glucose' 

 the sugar 'currency' of the plant, cane sugar its 'banking reserve.' 



"The immediate result of the diastatic transformation of starch is 

 not glucose, but maltose. But Mr. Horace Brown has shown in his 

 remarkable experiments on feeding barley embryos that, while they can 

 readily convert maltose into cane sugar, they altogether fail to do this 

 with glucose. We may conclude, therefore, that glucose is, from the 

 point of view of vegetable nutrition, a somewhat inert body. On the 

 other hand, evidence is apparently wanting that maltose plays the part 

 in vegetable metabolism that might be expected of it. Its conversion 

 into glucose may be perhaps accounted for by the constant presence in 

 plant tissues of vegetable acids. But, so far, the change would seem 

 to be positively disadvantageous. Perhaps glucose, in the botanical 

 sense, will prove to have a not very exact chemical connotation. 



"That the connection between cane sugar and starch is intimate is a 

 conclusion to which both the chemical and the botanical evidence seems 

 to point. And on botanical grounds this would seem to be equally 

 true of its connection with cellulose. 



"It must be confessed that the conclusion that 'cane sugar' is the 

 first sugar to be synthesized by the assimilatory processes seems hard 

 to reconcile with its probable high chemical complexity, and with the 

 fact that, botanically, it seems to stand at the end and not at the begin- 

 ning of the series of metabolic change." 



PROTOPLASMIC CHEMISTRY. 



The synthesis of proteids is the problem which is second only in 

 importance to that of carbohydrates. Loew's views of this deserve 

 attentive study. Asparagin, as has long been suspected, plays an 

 important part. It has, he says, two sources in the plant. "It may 

 either be formed directly from glucose, ammonia (or nitrates), and sul- 

 phates, or it may be a transitory product between protein decomposition 

 and reconstruction from the fragments" (loc. cit., 64). 



