266 EXPERIMENT STATION RECORD. 



"The liver of the embryo i)ly coutaius adeuase, even in Its early stage of de- 

 velopment, but no guanase. In this respect it shows the s])ecific character of 

 the liver of the adult animal. 



" An extract of embryo viscera, other than the liver, readily gives indication 

 of the presence of guanase at an early age. 



" The unlike distribution of these two enzym reactions under comparable con- 

 ditions of experiment give further evidence in favor of the existence of two 

 distinct and specific deamidizing enzyms. 



" It has not been possible to demonstrate the formation of uric acid from 

 preformed or added puriu bases (adeuiu or hypoxauthiu) by extracts of em- 

 bryonic tissues. The preliminary oxidative transformation of hypoxanthiu 

 to xanthin is likewise doubtful. Xantho-oxidase is not present in the em- 

 bryo visceral organs of the pig; it is found, however, in the livers of the full- 

 grown and suckling animals of the same species. The latter readily form uric 

 acid from purins under suitable conditions. 



" The uricolytic enzym has not been found in extracts of embryo pig tissues 

 under conditions in which it is readily identified in the adult organs. The 

 enzym appears either shortly before or after birth. These observations speak 

 in favor of the specific uricolytic power of tissue extracts, and indicate that 

 the destruction of uric acid in such solutions is not solely due to the alkalin re- 

 action, etc., of the digesting medium. 



" The tardy appearance of the oxidative and katabolic enzyms concerned in 

 the transformation of the purins is suggestive as a characteristic of growing, 

 synthetic organisms." 



Chemical studies on growth. Ill, The occurrence of g'lycogen in the 

 embryo pig, L. B. ]\[endel and C. S. Leavenworth (Anier. Jour. Physiol., 20 

 {iy08), No. 1, PI). 117-126). — Quotations from the authors' summary of their 

 paper follow : 



"The . . . experiments [reported] can not be interpreted as giving evidence 

 that a large glycogen content is a characteristic of embryonic structures or 

 developing tissues ; for the tissues, examined by adequate methods, show no 

 unusual richness in this carbohydrate. The distribution is not markedly differ- 

 ent from what pertains in the adult animal, except that the liver does not 

 assume its glycogen-storing function early, at least in the pig. This conclusion 

 seems as reasonable, in the absence of direct contradictory evidence, as to 

 attribiite the uniformly noted poverty in hepatic glycogen entirely to the defi- 

 cient nutrition of the maternal animal, . . . The metabolism of glycogen in the 

 embryo is doubtless comparable with its role in the nutrition of the adult ; and 

 it seems unnecessary to postulate any special formative property to account 

 for its presence. Glycogen may thus be regarded simply as a store of nutrient 

 energy rather than as a peculiar mark of histogenesis." 



Chemical studies on growth. IV, The transformation of glycogen by 

 the enzyms of embryonic tissues, L. B. Mendel and T. Saiki {A))ier. Jour. 

 Physiol., 21 (1908), No. 1, pp. 6J1-G8). — Liver muscle and blood from pig em- 

 bryos and liver from adult pigs were studied. The developing muscle tissue, 

 which contains glycogen during embryonic life, gave evidence during the early 

 stages of this period of a relatively greater glycogen-digesting power than that 

 of liver tissue, which is free from glycogen. 



" The principal feature to be emphasized in the present experiments is the 

 variable equipment of amylolytic enzyms in the embryonic tissues and its cor- 

 relation with developmental changes. The embryo liver, which is early free 

 from glycogen, only gradually acquires its characteristic digestive capacity, the 

 amylolytic efficiency increasing with gi-owth." 



