METABOLISM 29 



executing superfluous movements (note how he is con- 

 stantly twisting and untwisting his fingers, clasping 

 and unclasping his hands, or walking up and down the 

 room instead of sitting in an easy-chair). In all these 

 ways energy is expended, and the balance for ' savings ' 

 in the form of adipose tissue is reduced. It is in this 

 way that ' temperament ' affects ' physiological person- 

 ality'; or one might reverse the order of cause and 

 effect, and say, perhaps with equal truth, that it is the 

 possession of a protoplasm of unusual vital activity 

 which expresses itself inwardly by an active metabolism, 

 and outwardly by all the marks of the energetic 

 temperament. To the physician, at all events, the 

 metabolic peculiarities or physiological personality of 

 his patient is a factor of the greatest importance in 

 practice. 



QUALITATIVE METABOLISM. 

 1. Proteins. . 



Physiologists are as yet only beginning the investiga- 

 tion of the chemical changes which proteins undergo in 

 the body, and of the facts already ascertained but few 

 are capable of application in medicine. This line of 

 research, however, is now being actively prosecuted, and 

 there is every reason to hope that the results which 

 it will yield will soon throw a flood of light on many 

 of the obscure disorders of metabolism met with in 

 disease. In the following paragraphs an attempt will be 

 made to trace the life-history of the proteins in the body 

 so far as present knowledge permits. 



The protein of the food is first brought into solution 



