THE ORGANIC CONSTITUENTS OF MILK 35 



books dealing with physiological chemistry. The estimations 

 show a considerable degree of variation, but 3 per cent, appears 

 to be an average round figure for the caseinogen of cows' milk, 

 while for human milk i per cent, may be taken as a fair average. 

 In both cases, however, considerable variations both above and 

 below these figures are found. 



The published estimations of lact-albumin are less numerous 

 than those of caseinogen. The amounts of albumin in human and 

 cows' milk do not differ very widely, although it is usually greater 

 in human than in cows' milk. Broadly, in human milk there appears 

 to be about 0-5 per cent, albumin, the tendency being for the figure 

 to be higher. In cows' milk 0-5 per cent, is given by some ob- 

 servers as the figure for albumin, but, as a whole, it tends to be 

 rather lower. 



Lehmann stated that in human milk 29-4 per cent, of the total 

 protein was albumin, or 0-5 per cent, in the milk, while 70-6 per cent, 

 of the total protein was caseinogen, which equals 1-2 per cent, in 

 the milk. In cows' milk 9 per cent, of the protein was albumin, or 

 0-3 per cent, in the milk, while 91 per cent, of the total protein was 

 present in the form of caseinogen, or 3 per cent, in the original milk. 



The relative proportions of caseinogen and albumin are given 

 by Schlossmann, who, estimating the total nitrogen content of 

 human milk and its distribution on the twenty-fifth day after 

 parturition, assigned 35 per cent, of the nitrogen to the albumin 

 and 41 per cent, to the caseinogen. 



The same author, in another paper dealing with cows' milk, gives 

 the percentage amount of the three proteins as follows : 



Caseinogen Lacto -globulin Lact-albumin 



3-185 per cent. 0-154 per cent. 0*374 per cent. 



He found great resemblance between the albumin and the globulin, 

 and considers that for nutritional purposes the latter may be 

 neglected. 



Sidler assigns 43 per cent, of the total nitrogen in human milk 

 to caseinogen and 42 per cent, to the whey-proteins, the remainder 

 being non-protein nitrogen. 



The relatively high nitrogen content of milk during the colostral 

 period has already been considered, and occurs both in human 

 and cows' colostrum. There seems little doubt that colostrum 

 contains a higher percentage of caseinogen and whey-proteins than 

 later milk, but the evidence upon the amounts of these present 

 at this period is not conclusive, wide variations being obtained 

 by different authors. 1 



The work of Bauer (i, 3) and of Bauereisen on biological 

 lines renders it likely that there is also a relatively higher pro- 

 portion of whey-proteins in colostrum than in later milk. 



1 Cp. also Edlefsen and Sebelien. 



D 2 



