CHAP, ii Photosynthesis 305 



; If after all I regard the starch in the chlorophyll as one 

 of the first products of assimilation, it is not, therefore, to 

 be said that carbon dioxide and water unite forthwith to 

 form molecules of starch within the chlorophyll substance ; 

 oxygen being evolved. It is not even necessary that any 

 carbohydrate whatever should arise immediately ; it is 

 possible and probable that the process accompanied by the 

 evolution of oxygen is a very complicated one, from which 

 the formation of starch results only by numerous chemical 

 metamorphoses.' 



At the same time it must be said that Sachs did not show 

 any great readiness to accept the views of other workers. 

 In the Vorlesungen he said (Eng. ed. p. 318) : 



' Whether it is right to claim with Berthelot and Kekule 

 (1861) formic acid or some other member of the formyl group 

 as the first product of assimilation, I hold as very question- 

 able, and it has been hitherto proved by nothing. I lay 

 still less value on Pringsheim's so-called Hypochlorin. . . . 

 At any rate, even after all the recent researches, the fact 

 which I established twenty years ago, that the starch in the 

 assimilating chlorophyll is to be regarded as the first 

 distinctly recognizable product of assimilation, remains 

 unaltered. Even then I left the way open for further 

 knowledge, since I laid stress on the fact that it was a matter 

 of the first distinctly visible product, and that probably 

 other products hitherto not distinctly visible, however, 

 precede the formation of starch. Hence, even if, as a 

 matter of fact, formyl aldehyde . . . were actually an earlier 

 product of assimilation from which the starch is developed 

 in the chlorophyll, which is not the case, there still would 

 not be the smallest item to alter in the statements I have 

 made.' 



It is strange that, while he held these opinions, Sachs 

 ignored, or at any rate made no allusion to, the hypo- 

 thesis of Baeyer, with which he must have been acquainted, 

 published as it was several years earlier. 



Sachs said elsewhere, ' I am strongly inclined to assume 

 that both in the assimilating chlorophyll corpuscles and in 



GREEN U 



