AKIMAL PRODUCTIOK. 267 



Chemical studies on growth. V, The autolysis of embryonic tissues, L. B, 

 Mendel and C. S. Leavenworth {Amrr. Jour. Physiol., 21 (1908). No. /, pp. 

 69-76). — Using tissues from pigs and pig embryos, a number of studies were 

 made. " The equipment for autolytic tissue disintegration is present early in 

 the embryo, even if it is held in check by the normal environment and reaction 

 of the animal cells. . . . With the contention of certain investigators that these 

 enzyms play no part in metabolism during life we are not at present concerned." 

 Chemical studies on growth. VI, Changes in the purin, pentose, and 

 cholesterol content of the developing egg, L. B. Mendel and C. S. Leaven- 

 worth (Amer. Jour. Physiol., 21 {1908), No. 1, pp. 77-8-}). — Both hens' and 

 ducks' eggs wei'e used in the investigation undertaken to study the question of 

 purin synthesis in developing eggs. It was found that purin increased during 

 incubation, but not materially after hatching, in tests in which chicks were fed 

 for 2 weeks on a practically purin-free diet of bread crumbs. 



Determinations of the guanin, adenin, and hypoxanthin gave " further evi- 

 dence of the progressive synthesis of purins taking place during the growth of 

 the embryo, and they show that, as in the adult and embryo organs already 

 examined, guanin and adenin are the predominating bases involved." 



The proportion of pentoses was also found to increase during the incubation 

 period, while the total ether extract and cholesterol diminished. The studies 

 of fat constituents gave " no evidence of a synthesis of cholesterol in the 

 processes incidental to the development of the chick. On the contrary, the 

 cholesterol apiiears to disappear in p>H't in company with the rest of the 

 lipoid yoke substances which act here as sources of energy in growth," 

 Karlier work has been noted (E. S. R., 18, p. 660). 



Chemical studies on growth. VII, The catalase of animal embryonic 

 tissues, L. B. Mendel and C. S. Leavenworth {Amer. Jour. Physiol., 21 {1908), 

 No. 1, pp. 85-9^). — As in earlier studies of growth, material was obtained from 

 embryonic and adult pigs. The experimental data show the early presence of 

 the catalytic power in embryonic tissues, though considerable variations in the 

 catalytic power of different organs were noted. 



Chemical studies on growth. VIII, The occurrence of lipase in embryonic 

 animal tissues, L. B. Mendel and C. S. Leavenworth {Amer. Jour. Physiol., 

 21 {1908), No. 1, pp. 95-98). — The results obtained in the studies of material 

 from embryonic and adult pigs "gives evidence of the early presence of 1 lipase 

 in the liver and intestine of the embryo; but the activity of the extracts of 

 these tissues is decidedly less pronounced than that of the comparable material 

 from the full-grown animal." 



Chemical studies on growth. IX, Notes on the composition of embryonic 

 muscular and nervous tissues, L. B. Mendel and C. S. Leavenworth {Amer. 

 Jour. Physiol., 21 {1908), No. 1, pp. 99-104). — According to the authors, the 

 analytical data presented give further evidence of the comparatively high water 

 content of embryonic tissues. 



" Creatin is present in the embryonic muscle, the content being considerably 

 lower than in full-grown animals. 



"Among the purin bases obtainable from embryonic muscular structures, 

 adenin and guanin preponderate as in other organs. Hypoxanthin is found 

 free in the tissue, as in adult life. 



" Lactic acid can be separated from embryonic muscular tissue, but in ex- 

 ceedingly small amount. 



" The distribution of lipoids in the embryonic brain resembles that in ' gray ' 

 matter. Cholesterol is present at the earliest periods, while cerebrins are 

 entirely absent." 

 The materials studied were dliliiiiu'd from <'n)bryonic and adult pigs. 



