February 4, 



SCIENCE. 



155 



be a waste of time to attempt an explana- 

 tion of sleep on the basis of phenomena of 

 circulation. The best interests of Physiol- 

 ogy and Pathology demand that the system- 

 atic development of Comparative Physi- 

 ology be one of the physiological problems 

 of to-day. 



May I be pardoned for calling attention 

 to one special field of Comparative Physiol- 

 ogy which I believe to be especially fertile? 

 I refer to the field of Physiological Morphol- 

 ogy. I applied this name to the investi- 

 gation of the connection between the chem- 

 ical changes and the process of organization 

 in living matter. Two series of facts allow 

 us to connect these two groups of phenom- 

 ena : (1) The fact that phenomena of fer- 

 mentation lead to an increase in the num- 

 ber of molecules, and thus bring about an 

 increase of osmotic pressure in the cells. 

 This increase of osmotic pressure is the 

 source of energy for the work of growth. 

 (2) The facts of heteromorphosis, i. e., the 

 possibility of transforming in certain ani- 

 mals one organ into another or s^lbstitllting 

 one organ for another, through external in- 

 fluences, such as gravitation, contact, light, 

 etc. 



The exact and definite determination of 

 life phenomena which are common to plants 

 and animals is only one side of the physio- 

 logical problem of to-day. 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 pressure and the theory of the dis- 

 sociation of electrolytes. We know that 

 the peculiar phenomena of oxidation in liv- 

 ing matter are determined by fermentative 

 processes, and we venture to say that fer- 

 mentations form the basis of all life phe- 

 nomena. It has been demonstrated that 



fermentability is a function of the geomet- 

 rical configuration of the molecule. Sac- 

 charomyces cerevisije is a ferment for such 

 sugars only as have three, or a multiple of 

 three, atoms of carbon in the molecule. 

 Among the Hexaldoses only d-glucose, 

 d-mannose and d-galactose are fermentable, 

 while their stereoisomeres are not ferment- 

 able. But the influence of the geometrical 

 configuration goes farther. Voit has sug- 

 gested, and Cremer has demonstrated, that 

 there is a far-reaching parallelism between 

 the fermentability and assimilation of Car- 

 bohydrates. 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 proteids and nucleins is another of the 

 problems of Physiology which will contrib- 

 ute to the main problem, the analysis of the 

 constitution of living matter. I believe 

 that the influence of stereochemistry will 

 be more or less directly felt in many 

 branches of Physiology, in questions of he- 

 redity as well as in the theory of space sen- 

 sations, as E. Mach has already intimated. 

 Van 't Hoff's theory of osmotic pressure 

 permits an application of the law of con- 

 servation of energy to a class of phenomena 

 to which this law was hitherto inapplicable, 

 namely, the phenomena of growth, func- 

 tional adaptation, secretion, absorption 

 and even pathological processes, such as 

 oedema. The physiologists who thought 

 that the blood pressure determined secre- 

 tion could not understand why secretion 

 took place under a higher pressure than 

 the blood pressure. Comparative Physi- 

 ology shows that secretion does not de- 

 pend upon circulation, and the theory 

 of osmotic pressure indicates that the os- 

 motic pressure in the cells is more than 

 twenty times as high as the blood pressure. 

 The work of secretion is done by osmotic 

 pressure, and not by blood pressure. A 



