14 THE PROTEIN ELEMENT IN NUTRITION 



at least for sulphuric acid. Lastly, the liver eliminates ammonia 

 on treatment with weak alkalis, and more is obtainable from the 

 organ of a well-fed animal than from that of a fasting animal 

 more also from carnivora than in the case of herbivora. 



It is known that during the constant disintegration of living 

 tissue, or autolysis, bodies of an acidic nature are produced 

 carbonic acid, lactic acid, etc. ; therefore, by applying the above 

 considerations to what is known to occur during digestion and 

 metabolism, it will be evident that, so long as an animal is well 

 nourished, there will be an excess of ammonia present, and the 

 tissues will show no signs of acidity. This excess, however, will 

 gradually disappear if the animal is deprived of food. A stage 

 will soon be reached when the production of acid exceeds the 

 amount of ammonia available for neutralization. Owing to the 

 acidity, autolysis will be set up, and amino-acids will be liberated. 

 These amino-acids would be carried to the alimentary tract, and 

 ammonia would be split off, as in the case of the products of 

 tryptic digestion. This ammonia, by restoring the alkalinity of 

 the liver and tissues, would inhibit the autolytic processes. 

 Degradation of tissue should proceed at a definite uniform 

 rate. 



From his results Schryver arrives at the following conclusion : 

 In order to maintain nitrogenous equilibrium, nitrogenous 

 foodstuffs must be ingested in such quantities and in such form 

 that the amount of ammonia produced therefrom in the digestive 

 tract is sufficient to maintain the intracellular alkalinity of the 

 liver, and probably other tissues. 



If this view is correct, it would mean that the ammonia split 

 off from the final products of tryptic digestion plays an important 

 role in nutrition, as it maintains the general intracellular alka- 

 linity, in the absence of which nitrogenous equilibrium ceases to 

 be longer possible. When the protein offered in the food is 

 deficient in either quantity or quality, the acidic processes 

 generated in the organism set going the autolytic enzymes ; the 

 amino-acids thereby liberated are carried to the side-chains of 

 the bioplasm of the cells of the small intestine, keeping them 

 fully saturated even in starvation, and free ammonia is generated 

 by the hydrolysis or oxidation of those bodies they replace. 

 This ammonia inhibits temporarily the further disintegration of 

 the tissues, and so long as present in sufficient amount would 

 favour anabolism. The anabolism and katabolism of the tissues 



