10 STUDIES IN PLANT RESPIRATION AND PHOTOSYNTHESIS. 



not digested by gastric juice. He thus finds that in germinating 

 seeds the rate of carbon-dioxid emission is proportional to the 

 amount of protein indigestible in gastric juice when the supply 

 of carbohydrates is ample. While these studies are of prehminary 

 nature and the methods^ arbitrary and quite lacking in precision, 

 they are nevertheless suggestive of many interesting relations. 



The fundamentally important questions in both respiration and 

 photosynthesis are those relating to the dynamic aspect of these 

 phenomena. Both of these processes are primarily of interest 

 because they represent the energy transfer of life phenomena. 

 Without such energy transfers no manifestiatons of life could be 

 possible. Just as in physics and chemistry, energetics is being 

 recognized as the key to both the structure and behavior of matter, 

 so in physiology further development awaits a more comprehensive 

 conception of energetics. For a long time physiological chemistry 

 consisted in the study of the substances which enter into this device 

 of energy transformation and the products which leave it in the form 

 of excreta; it is now more and more attempting to study the chemical 

 phenomena which underlie the activity of such energy changes. 

 By tradition the behavior of protoplasm is associated with the com- 

 plex reactions of the proteins. The most complex group of carbon 

 compounds, it is also by inference the medium for the intricate 

 reactions of life processes. Etymologically, proteins are the sub- 

 stance of "first importance." Perhaps there is here a fundamental 

 difference between plants and animals, but, at any rate, it is very 

 doubtful whether in plants a preponderant role can be ascribed to 

 the proteins. From the chemical viewpoint the conception of 

 living matter presents many insurmountable difficulties, while, on 

 the other hand, the idea of a complex of coordinated chemical reac- 

 tions taking place in a material medium falls within the domain of 

 modern physical-chemical reasoning. If "living matter" is pos- 

 sessed of properties and forms of energy sui generis, the disciplines 

 of physics and chemistry can be of very Uttle aid in interpreting the 

 behavior of Uving things. As long as we are working on a basis of 

 physics and chemistry it is of little value to introduce conceptions 

 into physiology which have no sound foundation nor direct analogues 

 in these sciences. Thus to ascribe the energy of life processes to 

 "bio tic energy" is certainly not clarifying our conceptions of these 

 processes on the basis of physical science. The fact that physiolo- 

 gists are frequently having recourse to the coining of new phrases, 

 not found in the physical sciences, to describe life processes ought 



• For the action of pepsin and trypsin on plant protoplasm, cf. W. Beidebmann, Microchemische 

 Beobacthungen an den Blattzellen von Elodea. Flora, 11-12, 604 (1918). Walter, H. 

 Bioehem. Zeitachr., 122, 86-99 (1921). 



