1898 | BRIEFER ARTICLES 55 
and the eyes. Sleep is a phenomenon which occurs in insects and 
plants, and it would be a waste of time to attempt an explanation of 
sleep on the basis of phenomena of circulation. The best interests of 
physiology and pathology demand that the systematic development of 
comparative physiology be one of the physiological problems of today. 
May I be pardoned for calling attention to one special field of com- 
parative physiology which I believe to be especially fertile. 1 refer to 
the field of physiological morphology. 1 applied this name, to the 
investigation of the connection between the chemical changes and the 
process of organization in living matter. ‘Two series of facts allow us to 
connect these two groups of phenomena: (1) the fact that phenomena 
of fermentation lead to an increase in the number of molecules and thus 
bring about an increase of osmotic pressure in the cells, this increase of 
osmotic pressure being the source of energy for the work of growth : 
(2) the facts of heteromorphosis, z. ¢., the possibility of transforming in 
certain animals one organ into another or substituting one organ for 
another through external influences, such as gravitation, contact, light 
Cre. 
The exact and definite determination of life phenomena which are 
common to plants and animals is only one side of the physiological 
problem of today. The other side is. the construction of a mental 
picture of the constitution of living matter from these general qualities. 
In this portion of our work we need the aid of physical chemistry and 
especially of three of its theories ; stereochemistry, van ’t Hoff’s theory 
of osmotic pressures, and the theory of the dissociation of electrolytes. 
We know that the peculiar phenomena of oxidation in living matter are 
determined by fermentative processes, and we venture to say that fer- 
mentations form the basis of all life phenomena. It has been demon- 
strated that fermentability is a function of the geometrical configura- 
tion of the molecule. Saccharomyces Cerevisia is a ferment for such 
sugars only as have three or a mutiple of three atoms of carbon in the 
molecule. Among the hexaldoses only 8-glucose, -mannose, and 8-gal- 
actose are fermentable, while their stereoisomers are not fermentable. 
But the influence of the geometrical configuration goes farther. Voit 
has suggested and Cramer has demonstrated that there is a far-reaching 
parallelism between the fermentability and assimilation of carbohy- 
drates. Higher animals as well as yeast cells are able to form glycogen 
from such carbohydrates as are fermentable by yeast. The further 
development of these stereochemical relations and their extension to 
