TRANSACTIONS OF SECTION K. 849 



from the study of the nutrition of bacteria, arrived at some general conclusions in 

 the same direction. Bokorny appears recently to have similarly experimented on 

 algae. Neither writer, however, seems to have been acquainted with Acton's work. 

 The general conclusion which I draw from Loew is to strengthen the belief that 

 form-aldehyde is actually one of the first steps of organic synthesis, as long ago 

 suggested by Adolph Baeyer. Plants, then, will avail themselves of ready-made 

 organic compounds which will yield them this body. That a sugar can be con- 

 structed from it has long been known, and Bokorny has shown that this can be 

 utilised by plants in the production of starch. 



The precise mode of the formation of form-aldehyde in the process of assimi- 

 lation is a matter of dispute. But it is quite clear that either the carbon dioxide 

 or the water, which are the materials from which it is formed, must suffer dissocia- 

 tion. And this requires a supply of energy to accomplish it. Warington has 

 drawn attention to the striking fact that in the case of the nitrifying bacterium, 

 assimilation may go on witliout the intervention of chlorophyll, the energy being 

 supplied 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 o.xide like haemoglobin, and 

 so facilitating the dissociation. 



Chlorophyll itself is still the subject of the 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 proto-carbo- 

 hydrate are still obscure. Brown and Morris have arrived at the unexpected con- 

 clusion that ' cane-sugar is the first sugar to be synthesised by the assimilatory 

 processes.' I made some remarks upon this at the time,^ 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." Cane-sugar 

 the botanist 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 ftjeding 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 disadvan- 

 tageous. 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 synthesised 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 beginning of the series of metabolic change.' 



Pkotoplasmic 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 lias, he says, two sources 



' Journ. Chem. Soc, 1893, 673. = Kew BnUctln, 1891, 35-41. 



1895, ' 3 I 



