600 EXPERIMENT STATION RECORD. 



Chemical studies on growth, L. B. Mendel {Brit. Med. Jour., 1906, No. 2309, 

 pp. 17S1\ nss). — A ])aiH'r was presented at the meeting of the British Medical 

 Association at Toronto, 1!)0(5, which summarized the investigations of the author 

 and his coworkers which have to do with tlie composition and the chemical 

 changes which are characteristic of developing organisms and the equipment of 

 such organisms for utilizing the imtritive materials presented to them. 



The investigations of hens' and ducks' eggs after varying periods of incuba- 

 tion have furnished new evidence regarding the synthesis of purins in embry- 

 onic forms. The fresh egg is practically fi-ee from purins. The quantities of 

 purins gradually increase during incubation until the young are fully hatched. 



The specific purin compounds which especially are synthesized as a part 

 of the newly-formed nucleoproteid constituents ai-e guanin and adenin, traces 

 only of hypoxanthin being obtained. . . . We have found that the liver 

 tissue of the embryo (pig) has apparently not yet acquired the capacity of 

 destroying uric acid to any considerable extent, if at all — in striking contrast 

 with comparable material from adult animals. . . . One may conclude that 

 the embryonic organs, such as the liver, are early etiuipped for the preliminary 

 reactions in purin synthesis and degradation, in harmony with the extreme rich- 

 ness of the embryonic liver morphologically in nuclear materials. 



" Nucleic acids are characterized by the presence of pentose groups, as well 

 as purin complexes. The egg itself is practically free from furfurol-yielding 

 compounds. With the progress of incubation pentose groups are synthesized, 

 as might I)e expected from the characteristic development of nuclear materials." 



The development of specific enzyms, the glycogen content of the embryo, and 

 lipoids are also considered. In general, " analyses of the water-free and fat- 

 free tissues of animals fed on diets of widely different character indicate the 

 tendency of the tissues to maintain a constant chemical character." 



Metabolism experiments with organic and inorganic phosphorus, J. A. 

 LeClerc and V. ('. Cook (Jour. Biol. Client.. 2 (1906), No. 3, pp. 203-216).— 

 Studies were made with 2 rabbits and a dog in which inorganic phosphorus 

 in the form of disodium phosphate and such oi'ganic phosphorus compounds as 

 occur in w^heat bran and in egg yolk were compared. In the authors' opinion 

 the experiments point to the following conclusions: 



The amount of nitrogen retained is generally lowered by the addition of 

 inorganic phosphorus when fed with a normal food. The nitrogen balance 

 is not necessarily negative. 



In the case of food supplying little phosphorus, the addition of inorganic 

 phosphorus decreases the digestibility of the nitrogen and the nitrogen and 

 phosphorus balances are usually negative. 



Organic phosphorus favors nitrogen metabolism and increases the nitrogen 

 and phosphorus retention, especially in the case of the food supplying little 

 phosi)horus. Organic phosphorus, therefore, is more favorable to nitrogen and 

 phosphorus retention than is inorganic phosiihorus. The jihosphorus of wheat 

 bran appears to l)e a most valuable food constituent. 



The nitrogen of bran was poorly assimilated. The loss of nitrogen during 

 the periods in which bran was fed agree with earlier work, showing the low 

 digestibility of bran nitrogen and corroborate the results obtained regarding 

 the absorption of bran phosphorus. 



The nitrogen and phosphorus balances do not run parallel in all cases; the 

 general tendency is in that direction. 



In no case was there any retention of the added jihosphorus, whether fed 

 in the organic or in the inorganic form, when given with a food containing a 

 normal amount of phosphorus. 



