590 



LECTURE XXV. 



It is evident from these values that the urine during these five days 

 showed a very constant composition. It would be very interesting to 

 carry out such experiments with a uniform diet, and especially with the 

 same kind and amount of albumin, also on a large scale during patho- 

 logical conditions. In such a way we should obtain an insight into the 

 cell-metabolism under different conditions. At the same time it is not 

 true that we can draw very far-reaching conclusions in all cases as to the 

 cell-metabolism from the composition of the urine. We must always 

 remember how little we know concerning cell-metabolism and of the 

 dependence of one organ upon another. It is indeed possible that 

 there is an exchange of material in such a way that the decomposi- 

 tion-products from one organ are utilized by another. Thus there may 

 be a considerable destruction of tissue of certain specific composition, 

 which would not show any indication in such an analysis, because there 

 might not be any of the products from the destruction of this tissue, 

 in the urine. The kidney may be an economizing organ of the animal. 

 It is perfectly possible that the constituents which it receives that 

 are useful in the organism are in some way transformed and given 

 back to the circulation. We will recall the fact that the kidneys are 

 capable of effecting syntheses. Their cells conjugate benzoic acid with 

 glycocoll. Is there any reason for believing that this is the only syn- 

 thesis which the kidneys are capable of effecting? We will also mention 

 the fact that the animal organism is exceedingly economical with its 



