78 Ingvar Jorgensen and Walter Stiles. 
literature of the subject sufficiently indicates, and it is not unusual 
to find Baeyer’s hypothesis almost accepted as an axiom in 
biological text-books. Here again we agree with Spoehr who 
expresses as his opinion, “ In recent years this hypothesis has 
largely directed the course of the investigations in this subject, 
and it seems to the writer, to the detriment of critical and inde¬ 
pendent thinking on the broader aspects thereof.” 
B. Hypothesis of Baeyer. 
We shall in what follows only deal with Baeyer and his 
followers as briefly as possible, as those interested in this branch 
of this subject will have no difficulty in finding ample references to 
the literature in text-books and journals. 
Before Baeyer’s time the chemists, for instance, Liebig (1843b), 
Kolbe and Schmidt (1861), and Berthelot (1864), appear to have 
been of the opinion that in the process of assimilation organic acids 
were produced from which carbohydrates were subsequently 
formed. In the course of a paper, entitled “ Ueber die Wasserent- 
ziehung und ihrer Bedeutung fur das Pflanzenleben und die 
Gahrung,” Baeyer threw out a suggestion as to the formation of 
formaldehyde as an intermediate product of assimilation, a hypothesis 
which was really based on Butlerow’s observation (1861) that 
trioxymethylene (a condensation product of formaldehyde) on 
heating in alkaline medium yields a syrupy product with some of the 
properties of sugars. 
We give below Baeyer’s suggestion in a translation of his own 
words. 
“ The general assumption in regard to the formation in the 
plant of sugars and related bodies, is that in the green parts carbon 
dioxide under the action of light is reduced and by subsequent 
synthesis transformed to sugar. Intermediate steps have been 
sought in organic acids: formic acid, oxalic acid, tartaric acid, 
which can be regarded as reduction products of carbon dioxide. 
According to this opinion, at those times when the green parts of 
the plant are most strongly subjected to the action of the sun’s rays, 
a strong accumulation of acids should take place, and these should 
then gradually give place to sugar. As far as I know this has 
never been observed, and when it is remembered that in the plant 
sugars and their anhydrides are formed under all circumstances, 
whereas the presence of acids varies according to the kind of plant, 
the particular part of it and its age, then the opinion already often 
put forward, that the sugar is formed directly from the carbon 
dioxide, increases in probability. 
