THE INFLUENCE OF INANITION ON 



METABOLISM. 



PART 1. INTRODUCTION. 



In the processes of life the transformations of matter with the energy 

 changes dependent upon them are of two markedly different kinds katabolism 

 or the breaking down of body material, and anabolism, or the construction 

 of body material. Considering the body as consisting not only of the skeleton, 

 muscles, glandular, adipose, and other tissue, but also of the fluids, such as 

 blood and lymph, it is perfectly proper to consider katabolism as that process 

 by which body material is broken clown as a result of oxidation and cleavage. 

 Although under certain conditions of inanition there may be distinct anabolic 

 processes occurring in the body, such as the much discussed formation of fat 

 and sugar from proteid, yet in general it is customary to assume that anabolism 

 follows the ingestion of food. This anabolic process consists in taking certain 

 molecular complexes, such as those in the protein, fat, and carbohydrate of food, 

 and rearranging the fragments of the molecules in such a manner that the 

 re-formed materials are of a molecular composition best suited to or comparable 

 with the structure of the body. While the molecular structures of the protein, 

 fat, and carbohydrate of the food are in general similar to those of the body 

 materials, differences indeed material differences are not lacking. Perhaps 

 in no group is this lack of complete uniformity of structure more striking than 

 in the case of protein. Eecent investigation of the cleavage products in the 

 animal and vegetable proteins 1 shows wide differences in the kinds and amounts 

 of the molecular complexes of which these intricate molecules are composed. 



It is evident, therefore, that the final products of metabolic activity of the 

 living body are the resultants of the anabolic and katabolic transformations 

 which take place. Hence each study of metabolism is a twofold problem in which 

 is considered, first, katabolism, or the actual disintegration of body material; 

 second, anabolism, or the transformation of food materials into body material. 

 Since under normal conditions these two processes are continually occurring 

 side by side and their influences are correspondingly interrelated, it is emi- 

 nently desirable, if possible, so to adjust the conditions of experimentation as 

 to eliminate the complex relations necessarily existing between the processes of 

 anabolism and katabolism. 



1 Osborne & Gilbert, Amer. Journ. Physiol. (1906), 15, p. 333. 



