FOODS HUMAN NUTRITION. 569 



Nuclein synthesio in the animal body, E. V. McCoLtuM [Wisconsin Sta. 

 Research Bui. S, pp. 75-93). — Experimeuts on nuclein metabolism were under- 

 taken of which the primary object was to limit the phosphorus supply to inor- 

 ganic forms. The author believes that a ration composed of pure proteins, fats, 

 carbohydrates, and the necessary salts could be made sufficiently palatable to 

 insure a satisfactory intake and utilization of food. Many devices consistent 

 with the experimental conditions were resorted to in order to change the taste 

 and relieve the monotony of the food supplied from day to day. Half grown 

 rats, younger rats, and a matured rat were used in the different series. 



Edestin, zeiu, glucose, purified butter fat, cane sugar, milk sugar, cholesterin, 

 and ash of milk were some of the materials used in the ration, while calcium 

 phosphate, and sodium chlorid were always added and ferric chlorid at inter- 

 vals. The ration, as the author notes, contained no purins. For purposes of 

 comparison, half grown rats were also fed the ration together with purin bases 

 prepared from liver and an amino acid mixture from the hydrolysis of beef 

 muscle. 



Control tests were made on a ration in which casein was used to supply 

 phosphorus and on a so-called normal ration. 



Analyses were made of the carcasses of 9 of the rats and in the case of one of 

 the rats the amount of phosphorus excreted was determined and found to be on 

 an average 0.0063 gm. per day during a period of 8 days. 



According to the author's summary, the data furnished by his experiments 

 seem to warrant the following conclusions : 



" The palatability of the ration is a most important factor in animal nutrition. 

 Without palatability the ration may possess all the necessary food ingredients 

 and yet fail to nourish an animal properly. 



" The failure of previous efforts to maintain animals on a mixture of rela- 

 tively pure proximate constituents of our foodstuffs was due to the lack of 

 palatability of such mixtures. 



" When sufiicient care is given to changing the character and flavor of the 

 food supplied in such simple mixtures, it is possible to induce an appreciable 

 amount of growth. 



" Very young animals adapt themselves to a ration possessing a low degree 

 of palatability much better than do adults. 



" Other things being satisfactory, all the phosphorus needed by an animal for 

 skeleton, nuclein or phosphatid formation, can be drawn from inorganic 

 phosphates. 



" The animal has the power to synthesize the purin bases necessary for its 

 nuclein forn^ition from some complexes contained in the protein molecule, and 

 does not necessarily use purin bases of exogenous origin for this purpose." 



Experimental variation of intestinal flora by changes in diet, C. A. IIerter 

 (Internat. Beitr. Path. u. Ther. Ernahrungsstor. Stoffw. u. VcrdauuHgHlmul;., 1 

 (1910), yo. 3, pp. 275-281).— In this paper the author summarizes and discusses 

 investigations carried on in his laboratory. 



" The bacterial changes in the intestine, the products of putrefaction and the 

 clinical conditions may thus be varied at will by changing from a protein to a 

 dominantly carbohydrate diet, and an exact reversal of the conditions may be 

 Induced by changing from a carbohydrate diet back to a protein diet." The 

 author believes that one of the most interesting features of his work is " the 

 extensive bacterial degeneration which follows the change from one diet to 

 another. It seems . . . possible that in conditions of disease of the intestinal 

 tract where certain undesirable bacteria abound, both on a protein diet and on 

 a milk diet rich in carbohydrates, frequent alternations in the chemical nature 



