CHAP. IX,] 



THE CONTRACTILE TISSUES. 



393 



III. For four days they returned to the normal occupation >a*d 

 diet of period I. 



IV. During two days they were again put on a non-nitrogenous 

 diet, and made to perform a long march each day, with intervals 

 of rest. 



V. They again returned to their normal occupation and diet. 



The diet was not limited ; the men took what they needed. The 

 nitrogenous excreta of urine and faeces were carefully determined ; 

 and periods II. and IV. were then compared as to the nitrogen 

 excreted. 



We may illustrate this comparison by the numbers relating to one 

 of the soldiers experimented upon. 



TOTAL DRY FOOD FOR THE TWO DAYS OF THE RESTING AND 

 WORKING PERIOD, IN KILOG. 



WATER, IN KLLOG. 



TOTAL EXCRETION OF NITROGEN, IN GRMS. 



Conclu- 

 sions. 



From these tables it appears that there is a slight 

 total increase of nitrogen eliminated during muscular 

 exertion. It must be remembered that more non-nitrogenous food 

 was at the same time taken into the system, and more fluids were 

 drunk. Both these circumstances, apart from muscular exercise, 

 imply the use of digestive and assimilative apparatus which like 

 muscles are mainly nitrogenous in constitution. 



In the second set of experiments the fluid and solid diet 

 (including 19'61 grms. of nitrogen) was constant during the whole 

 time. 



