MAINTENANCE REQUIREMENTS OF MATTER 337 



Third, the considerable amount of hippuric acid produced 

 by herbivora makes a very considerable draft upon the organism 

 for bases. Thus, in four experiments by Diakow cited by 

 Zuntz, it was equivalent to from J to f of the total excess of 

 bases over inorganic acids in the urine. 



Fourth, in the katabolism of the proteins, nucleo-proteins 

 and other compounds containing sulphur and phosphorus, 

 these elements are largely oxidized to sulphuric and phosphoric 

 acids. The sulphur of one pound of protein having the com- 

 position of serum albumin, for example, if fully oxidized, would 

 yield the equivalent of nearly one ounce by weight of con- 

 centrated sulphuric acid. High protein rations, therefore, 

 tend to bring about a loss of bases from the body. 



b. Neutralization of acids. In all these various ways there 

 is a constant tendency to disturb the neutrality of the body 

 fluids and towards the establishment of an acidosis, to prevent 

 which the acids must be neutralized. The significance of 

 this was first shown by the experiments of Lunin already re- 

 ferred to (421), which showed that the life of animals fed on 

 ash-free feed could be considerably prolonged by the addition 

 of sodium carbonate to neutralize the acids produced in the 

 body. Normally, this neutralization is accomplished in two 

 general ways. 



First, an excess of acid may be combined with the ammonia 

 which is produced from the amino acids in the katabolism of 

 protein (233) and is subsequently converted into urea in the 

 liver. A part of this ammonia, however, may be diverted 

 from this course and utilized to neutralize acids, the resulting 

 ammonium salts being excreted in the urine in place of a cor- 

 responding amount of urea. The ammonia arising from the 

 putrefactions in the lower intestines (140) may serve the same 

 purpose. A small quantity of ammonium salts, arising from the 

 neutralization of the acids produced especially in the protein 

 katabolism, is normally found in the urine, while the feeding 

 of inorganic acids or their injection into the blood stream, or a 

 pathological acidosis, may greatly increase their amount. ; 



On the basis of early experiments upon rabbits it has been taught 

 that the ability to neutralize acids by means of ammonia is peculiar 

 to carnivora and omnivora and is present to a very limited extent in 

 z 



