CHEMICAL DYNAMICS OF ANIMAL NUTRITION 161 



(ii) It is inhibited by the action of ammonia and other 

 alkalis, but accelerated by the presence of acids, 

 especially lactic acid. 



(iii) This acceleration of acids is a function, in the case, 

 at any rate, of sulphuric acid, depending on the absolute 

 quantity of acid present, but not, except to a very 

 limited extent on the concentration (Part V, Experiment 

 Series V (f) p. 152). 



(iv) According to the researches of Nencki, Pawlow, and 

 Zaleski 2 , ammonia is formed as a product of nitrogen- 

 ous metabolism in the alimentary tract ; there is more 

 ammonia in the portal vein than in any other part of 

 the vascular system. The liver, furthermore, eliminates 

 ammonia on treatment with weak alkalies, and more of 

 this body is obtainable from the organ of a well fed 

 animal than from that of a fasting animal. The numbers 

 are lower in the case of herbivora than in the carnivora. 



These facts offer a ready explanation as to the way in which the 

 supply of products of albumen degradation can be maintained for the 

 saturation of the bioplasm with nitrogenous side-chains in the mucous 

 membrane of the intestine and other organs. Nencki, Pawlow, and 

 Zaleski, show that the liver of a dog on treatment with weak alkalis 

 at 4OC, yields on an average 26 mg. of ammonia per 100 gm. of tissue 

 if the animal be killed shortly after a heavy meat meal, about 7*6 mg. 

 if fed on bread and milk only, and about 7*3 mg. if killed during a fast. 



The numbers are equivalent to ro and 0*3 mg. NH S for 4 grams 

 of tissue, quantities which require 0^0028 and 0*0008 gm. sulphuric 

 acid for neutralization. 



Now, on reference to Experiment Series V (<?), Part V, (p. 150) it 

 will be seen that in the case of cats, 20 c.c. H !i so 4 containing 

 0*0030 gm. acid, a quantity only just sufficient to neutralize 1*0 mg. 

 ammonia, exerts but little influence on the rate of autolysis, whereas 

 the same volume - - acid produces a marked acceleration. (There 

 will, of course, be small quantities of sodium carbonate and other 



