82 Ingvar Jorgensen and Walter Stiles. 
C. Suggestion of van’t Hoff. 
Baeyer’s hypothesis is based on the synthesis of carbohydrates 
in the laboratory by ordinary chemical processes. It is difficult, 
as we have pointed out, to imagine that the laboratory conditions 
required for this synthesis should he comparable with those in the 
plant. Much more stimulating and interesting therefore, is the 
suggestion of van’t Hoff that the reversible enzyme action is a 
characteristic of many reactions in the plant. It is not clear from 
the few remarks of van’t Hoff in what manner he thought the 
photochemical reaction and synthetic enzyme reaction should 
co-operate in the production of carbohydrates. His main interest 
appears to have centred on the problem as to the substances from 
which the main products of assimilation could have been synthesized 
by enzyme reaction. So for instance at a lecture in Dusseldorf in 
1898, he said “ It was pointed out by Tammann that under the 
action of emulsin, amygdalin is only partially split and that this 
hydrolysis proceeds further if the products are removed. Perhaps 
if he had added a further amount of products of hydrolysis, he 
might have succeeded in synthesizing amygdalin. Duclaux put 
forward transformation formulae, which again suggest the attainment 
of an equilibrium, and Hill seems to have effected the synthesis of 
maltose from glucose by means of a yeast enzyme. Unless a 
ferment undergoes alteration of some kind during its period of 
activity, it follows, on theoretical grounds, that a condition of 
equilibrium and not one of total change must be brought about, 
and that therefore the opposite reaction must be induced. We are 
indeed justified in asking the question, whether (by application of the 
theory op equilibrium), under the influence of zymase and by exceeding 
a certain limiting opposing pressure of carbon dioxide, glucose might 
not be formed from alcohol and carbon dioxide, and moreover 
whether trypsin may not be able, under conditions prescribed by 
the theory of equilibrium, to form protein from the products of the 
hydrolysis, which it brings about under other conditions.” (Bayliss’ 
translation, 1914; the italics are our own.) 
It is to be regretted that this suggestion has not attracted the 
attention of plant physiologists as work on the lines indicated by 
van’t Hoff’s suggestion, would at least have been likely to result in 
lasting contributions to our knowledge of plant processes. Such 
work is of course considerably more difficult that the carrying out 
of qualitative tests for formaldehyde, which constitutes the bulk 
of the work done on behalf of Baeyer’s hypothesis. 
