HUMAN MILK. 663 



ing proteins and about 20 per cent for rest nitrogen. The principal part 

 of the rest nitrogen is considered as urea. 



From a quantitative standpoint, the most essential differences between 

 woman's and cow's milk are the following: As compared with the quan- 

 tity of albumin, the quantity of casein is not only absolutely but also 

 relatively smaller in woman's milk than in cow's milk, while the latter is 

 poorer in milk-sugar. Human milk is richer in lecithin, at least relatively 

 to the amount of protein. BUROW found 0.49-0.58 p. m. lecithin in cow's 

 milk and 0.58 p. m. in woman's milk, which corresponds to 1.40 per cent 

 for the first milk and 3.05 per cent for the second, calculated on the per- 

 centage of protein. NERKING and HAENSEL found as average for lecithin 

 in cow's milk 0.63 p. m. and in woman's milk 0.50 p. m. GLIKIN found 

 0.765 p. m. lecithin (phosphatides) as average for cow's milk and 1.329 

 p. m. for human milk. KOCH found that both human milk and cow's 

 milk contain lecithin as well as cephalin. The total quantity of both 

 bodies in human milk was 0.78 p. m. and in cow's milk 0.72-0.86 p. m. 

 The quantity of nucleon is greater in woman's milk. WITTMAACK claims 

 that cow's milk contains 0.566 p. m. nucleon, and woman's milk 1.24 

 p. m., and according to VALENTI the quantity of nucleon in human milk 

 is indeed still higher. SIEGFRIED finds that the nucleon phosphorus 

 amounts to 6.0 per cent of the total phosphorus in cow's milk and 41.5 

 per cent in woman's milk, and also that in human milk the phosphorus 

 is almost all in organic combination. This does not agree with the results 

 of SIKES who found on an average of only 42 per cent of the total P205 

 in organic combination. Because of the large amount of casein (and 

 calcium phosphate) cow's milk is much richer in phosphorus than human 

 milk. The relation P 2 05:N, according to SCHLOSSMANN/ is equal to 

 1 : 5.4 in human milk and 1 : 2.7 in cow's milk. Woman's milk is poorer 

 in mineral bodies, especially lime, and it contains only one-sixth of the 

 quantity of lime as compared with cow's milk. The mineral constituents 

 of human milk are better assimilated by the organism of the nursing 

 child than those of cow's milk. Human milk is also claimed to be poorer 

 in citric acid (ScHEiBE 2 ), although this is not an essential difference. 



Another difference between woman's milk and other varieties of milk is 

 UMIKOFF'S reaction, which seems to depend upon the quantitative composition, 

 especially the relation between the milk-sugar, citric acid, lime, and iron (SIBBER 3 ). 

 This reaction consists in treating 5 cc. of woman's milk with 2.5 cc. ammonia 



, Zeitschr. f. physiol. Chem., 30; Koch, ibid., 47; Wittmaack, ibid., 22; 

 Siegfried, ibid., 22; Nerking andHaensel, Bioch. Zeitschr., 13; G\ikm,ibid., 21; Valenti, 

 Biochem. Centralbl., 4; Schlossmann, Arch. f. Kinderheilkunde, 40; Sikes, Journ. 

 of Physiol., 34. 



2 Maly's Jahresber., 21. 



* Zeitschr. f. physiol. Chem., 30. 



