34 SCIENCE PROGRESS 



From his results it would appear that the maximum saving 

 of body nitrogen in terms of the nitrogen minimum is between 

 11-9 and 1 5*9 per cent. All his figures are considerably below 

 those given for the pig by McCollum {Amer. J. Physiol., 191 1, 

 29, 210), and the discrepancy cannot be explained except by 

 assuming a difference in the metabolism of the two species. 



Reference is made to the work of Grafe (191 2-14) and others 

 on the nitrogen-sparing action of simple nitrogen compounds 

 such as ammonium salts and urea, and it is shown that the 

 amount of nitrogen thus spared appears to be of the same order 

 as that spared with gelatin in Robison's experiments. The 

 suggestion is advanced that the action of gelatin may be of 

 the same nature as that of these simpler compounds, and consist 

 essentially in the reduction of the waste of amino-acids derived 

 from body-protein deamination and subsequent oxidation. 



Nitrogen of Urine. — An outcome of this work on gelatin, 

 which necessitated the determination of the minimum nitrogen 

 requirements, has been a contribution by Robison {Biochem. /., 

 1 922, 16, 1 3 1 ) on the distribution of the nitrogenous constituents 

 of the urine on low nitrogen diets. The results of this study 

 are in complete agreement with the well-known work of Folin 

 {Amer. J. Physiol., 1905, 13, 117). The values for the total 

 nitrogen are amongst the lowest on record. 



Pituitary Gland. — The much-debated question whether the 

 anterior lobe of the pituitary gland supplies a growth-promoting 

 or growth-regulating hormone still awaits a satisfactory answer. 

 The extensive work of T. Brailsford Robertson (/. Biol. Chem., 

 1916, 24, 285, 397, 409 ; 25, 647, etc.), who claims to have shown 

 acceleration of growth in young mice whose diet has been 

 supplemented with a small dose of the anterior lobe, and to 

 have isolated from this portion of the gland the active principle 

 which he termed tethelin, does not receive confirmation from 

 the investigation of Drummond and Cannan {Biochem. J., 

 1922, 16, 53). Tethelin as prepared by the latter workers, 

 following closely Robertson's method, is apparently a crude 

 mixture of lipoid substances. It is without any apparent 

 influence on the growth of young mice, nor did any appreciable 

 changes in the rate of growth follow the administration of the 

 fresh anterior lobe itself. Moreover, the statistical treatment of 

 Robertson's figures from which he derives his conclusions 

 appears to be of doubtful validity. 



Liver Lecithin. — Levene and Simms (/. Biol. Chem., 1922, 

 60, 285) record a valuable addition to Levene 's careful study of 

 the lecithins. It has already been shown that the unsaturated 

 fatty acids of the liver lecithins on hydrogenation yield stearic 

 and arachidic acids. From this and other data regarding the 

 iodine value and bromine addition compounds it was concluded 



