1919] FOODS — HUMAK NUTRITIOlsr. 465 



of Agriculture, at New York, Philadelphia, Boston, and Denver of the occurrence 

 of zinc and copper in oysters from various localities on the Atlantic seaboard, 

 the relation of zinc in oysters to the zinc content of the v^^ater in which they 

 grew, and the ratio of zinc to copper in oysters. 



Copper and zinc were determined in one weighed portion (100 gm.) of a 

 homogenous sample obtained by thoroughly comminuting at least a pint of the 

 oysters. After preliminary destruction of organic matter by the acid digestion 

 process, the copper was separated from the zinc by precipitation from slightly 

 acid solution with hydrogen sulphid, and the zinc determined by titration from 

 its chlorid with a standardized solution of potassium ferrocyanid. 



Zinc was found in all the oysters examined and was always associated with 

 copper. There appeared to be no direct relation between the zinc content and 

 the body weight of the oysters, nor uniformity of ratio of zinc to copper, nor 

 correlation between the zinc content of the oysters and the water in which 

 they grew. As the vegetable and organic matter dredged up with oysters in the 

 single locality studied contained considerable zinc and in some instances traces 

 of copper, the possibility is suggested that the zinc content of the oyster is an 

 indication of the character of its food rather than of the character of the sea 

 water in which it grows. "It seems probable that zinc, as well as copper, can 

 be absorbed and retained in the tissues of the oysters in quantities far in excess 

 of functional requirements, especially in oysters grown in waters badly polluted 

 with metallurgical and factory wastes." 



The blue or bluish green coloi-ation noticeable in some oysters is said to be a 

 reliable indicator of the presence of large amounts of copper and indirectly of 

 zinc, with which it is always associated. 



The normal existence of zinc in the human organism, C Ghigliotto (Ann. 

 Falsif., 12 {1919), No. 123-12^, pp. 12-14).— The author reviews conflicting 

 statements in the literature as regards the presence of zinc in the human body, 

 and reports the results of the examination of the viscera of 22 victims of ac- 

 cidental death. The content of zinc oxid found varied from 0.0015 to 0.0028 

 per cent of the viscera. Zinc was also found in a human and a bovine fetus. 

 This is thought to be an indication that zinc is a normal constituent not only of 

 the human organism biit of the animal organism in general. 



The nutritive value of yeast protein, T. B, Osborne and L. B. Mendel (Jour. 

 Biol. Chem., 38 (1919), No. 2, pp. 223-227, fig. jf).— The authors report that they 

 have kept rats successfully for more than a year, covering the period of growth, 

 upon a diet in which brewers' yeast furnished the sole source of nitrogen as 

 well as water-soluble vitamin. The yeast comprised from 30 to 40 per cent of 

 the ration, probably representing an actual protein concentration of less than 

 IS per cent. The nitrogen utilization as estimated by a comparison of the feces 

 Avith the intake was from 74 to S3 per cent. 



When bred with vigorous females which had grown up on a normal mixed 

 diet, two of the animals proved to be fertile but produced inferior young while 

 two others failed to breed. The testes of the latter showed an absence of gei-m 

 cells. The authors are, however, of the opinion that this infertility is not caused 

 by the yeast per se, and that there is no toxic factor present in the yeast. 



Is lactalbumin a complete protein for growth? A. D. Emmett and G. O. 

 LxjKOS (Jour. Biol. Chem., 38 (1919), No. 1, pp. 147-159, figs. 7).— Recent con- 

 flicting opinions as to the growtli-promoting value of lactalbumin are reviewed 

 and discussed, particularly those of Osborne, Mendel, et al (E. S. R., 37, p. 864) 

 that lactalbumin is a complete protein, and of McCollum, Simmonds, and Par- 

 sons (E. S. R., 40, p. 762) that it is incomplete and that the excellent results 

 obtained by Osborne and Mendel were due to the nitrogenous matter in the 

 protein-free milk employed. The present contribution to the question is the re- 



