8 METABOLISM OF ORGANIC AND INORGANIC PHOSPHORUS. 



phosphoric acid appear to be of varying characters. Most nucleins 

 are protein compounds, although a few do not contain protein. 

 Nucleins appear to occur mostly in the tissues, not in a free state, but 

 as compounds with protein as nucleo-albumins, and perhaps also 

 with lecithin, and the gastric digestion separates them from these 

 bodies. 



Whether the nucleins of the body tissues arise from the nucleins 

 of food (in which case they would rank among the number of essential 

 food substances), or whether the nucleins are formed in the body by 

 synthesis, is a question of great importance, about which, as in the 

 case of the mode in which the lecithins originate, very little is known. 

 The extensive observations by Miescher on Rhine salmon seem 

 to show that the nucleins as well as the lecithins arise in the animal 

 body by synthesis. 



PHOSPHO-GLUCO-PROTEIXS. 



This group includes the phosphorized gluco-proteins. These com- 

 pound proteins are decomposed by pepsin digestion and split off para- 

 or pseudo-nuclein substances, similar to nucleo-albumins. They 

 differ from the nucleo-albumins in that they yield a reducing sub- 

 stance on boiling with acids, and from the micleo-proteins in that 

 they do not yield purin bases. 



Only two phosphorized gluco-proteins are known at the present 

 time. Ichthulin, which occurs in carp eggs and was studied by 

 Walter, 6 was considered by him as vitellin for a time. In regard to 

 solubilities, ichthulin behaves like a globulin. Walter prepared a 

 reducing substance from the para-nuclein of ichthulin, which gave a 

 crystalline combination with phenylhydrazin. The other phospho- 

 gluco-protein is helico-protein, obtained from the glands of the small 

 snail Helix pomatia. 



INORGANIC PHOSPHOR I >. 



4 



In regard to phosphoric acid Hammarsten c states that there seems 

 to be no doubt that its importance lies chiefly in the fact that it takes 

 part in the formation of nucleins and thereby indirectly makes pos- 

 sible the processes of growth and division which are dependent upon 

 the cell nuclei. Loew d has shown, by means of cultivation experi- 

 ments on the alga Spirogyra, that only by supplying phosphates (in 

 this case potassium phosphate was used) was the nutrition of the cell 

 nucleus made possible, and thereby the growth and division of the 

 cells. The cells of the Spirogyra can be kept alive, and indeed produce 



Cited in Hammarsten 's Textbook of Physiological Chemistry, New York, 1908. 

 & Zts. physiol. Chem., 1891, 15 : 477. 

 c Physiological Chemistry, 2d ed., 1898. 

 <*Biol. Centrbl., 1891, 11: 269. 



