UTILISATION OF PROTEIDS IN THE ANIMAL 175 



proper to the species, I do not see how we can fail to deny this ; 

 while our developing conception of intracellular ferments acting 

 as weapons of the cell, and accounting for its dynamics, makes 

 the hypothesis of a difference of constitution between unstable 

 living and stable dead proteid less and less necessary. 



If we accept Folin's conceptions, we are at once at a distance 

 from Pfliiger's standpoint, and we are also well removed from 

 that of Voit. The modern theory explains better than Voit's 

 what is puzzling in the elimination of nitrogen, and so far as it 

 impinges on Voit's teaching it removes from it what was vague. 



If the views which are tempting us just now justify them- 

 selves, and if the organism really uses the dietetic proteid in 

 such a partial and selective manner, it seems to many that we 

 shall be compelled to divest the proteid of some of its dignity as 

 the pre-eminent foodstuff. Such views predispose us to accept 

 the results of experiments like those of Professor Chittenden, 

 which have become so familiar, indicating that the optimum 

 consumption of proteid is a good deal less than we should have 

 thought possible some years ago. This is a matter of practical 

 importance, and we must give such indications full consideration. 

 At the same time we must be cautious in coming to a conclusion 

 while our ignorance of detail is so great. Proteid as a source 

 of energy may show itself to be of no higher order than fats 

 or carbo-hydrates, and the amount actually needed for tissue 

 repair may be small ; but the demands of the body are complex, 

 and the constituents of proteid may have uses which come under 

 neither of these heads. What is the optimum supply for such 

 purposes we cannot even yet be said to know. 



References 



Abderhalden and Samuely, Zeitsch. f. physiol. Chem. xlvi. 193 (1905). 

 Bunge, Text-Book of Physiological Che?nistry. 2nd ed. of Translation 



by F. A. Starling, p. 168. 

 Cohnheim, Zeitsch. f. physiol. Chem. xxxiii. 451 (1901). 

 Fisher and Abderhalden, Zeitsch. f. physiol. Chem. xxxix. 81 (1903). 

 Folin, Amer. Journ. Physiol, xiii. 117 (1905). 

 Folin 2 , Zeitsch. f. physiol. Chem. xxxvii. 174 (1902). 

 Greenwood and Saunders, Journ. Physiol, xvi. 441 (1894). 

 Jacoby, Zeitsch. f. physiol. Chem. xxx. (1900). 

 Kutscher, Zeitsch. f. physiol. Chem. xxxix. 155 (1897). 

 and Seem an, Zeitsch. f. physiol. Chem. xxxiv. 528 (1902). 



