I &0 NUTRITION OF FARM ANIMALS 



the total sulphur exists in a less completely oxidized form 

 known as neutral sulphur, the nature and origin of which is 

 obscure. 



Phosphorus 



257. Forms ingested. The phosphorus supply of the body 

 is received substantially in the four forms indicated in Chapter 

 I (5), viz., as phosphates, as phosphatids, as phospho- and 

 nucleo-proteins and as phytin. Of these the various " organic " 

 forms usually predominate. 



It appears probable, however, that all these various forms of 

 phosphorus are resorbed into the blood stream in the form of 

 phosphoric acid. Of the phosphates ingested as such this is 

 certainly true. There seems good reason for believing that the 

 phosphoric acid radicle contained in the nucleic acid of the 

 nucleoproteins is quite completely split off by the digestive 

 enzyms and reaches the blood as phosphoric acid (139), and 

 the same thing is presumably true of the phosphoproteins. 

 The phosphatids are probably acted on by the Upases of the 

 digestive tract, but whether the glycerophosphoric acid resulting 

 from their cleavage is further split up is unknown. The ready 

 cleavage of phytin in seeds would suggest that probably its 

 phosphorus also is resorbed as phosphoric acid. 



258. Anabolism and katabolism. The animal body contains 

 a large store of phosphorus in the " inorganic " form, especially 

 in the skeleton. For the maintenance or increase of this store 

 the resorbed phosphoric acid is naturally available. 



The body also contains, however, organic phosphorus com- 

 pounds, which, although less in amount than the inorganic, 

 are of the highest significance for the vital functions. The be- 

 lief that the phosphorus supply of the body is resorbed chiefly 

 in the form of phosphoric acid necessarily implies, therefore, 

 that the organism is able to utilize inorganic phosphorus for the 

 synthesis of nucleic acids, phosphoproteins, phosphatids, etc., 

 and the experimental evidence is strongly in favor of this 

 belief (497). In this respect, as in many others, the synthetic 

 power of the organism appears to be greater than was long 

 supposed. 



Little is known regarding the course followed by the phos- 

 phorus in the katabolism of the nucleoproteins, phosphatids, 



