BODY TISSUES AND FLUIDS 



477 



content of protein and salts and a somewhat lower lactose content. The 

 following table, compiled largely from analyses made in Btmge's labora- 

 tory, nicely illustrates this point : 



RATE OF GROWTH AND COMPOSITION OF MILK 



Holt, Courtney and Fales have recently made a quite elaborate study 

 of the composition of human milk. A summary of some of their results is 

 given in the table below. As will be noted in the colostruni period human 



PERCENTAGE COMPOSITION OF HUMAN MILK BY PERIODS 



inilk has a high protein and high ash with rather low fat, in the transition 

 period the protein and ash are lower while the fat is higher, but after 

 one month the composition of normal milk does not vary in any essential 

 or constant way quite up to the end of lactation. The only striking 

 feature of late milk is a decline in quantity, though there is noted a 

 slight fall in all the solid constituents except the sugar. Of the different 

 constituents of milk, the least variation in both individuals and periods is 

 seen in the sugar. It will be observed in the table that the sugar amounts 

 to about 7.5 per cent, which is higher by a half per cent than the generally 

 accepted figure of 7 per cent. The greatest individual variations are 

 observed in the fat (figures from 1 to 6 per cent), although as recorded 

 above, the period variations in the fat are not marked. The protein is 

 highest in the colostrum period and falls to a little over half the propor- 

 tion in mature milk, during which period it is seldom over 1.25 per cent ; 

 of this about one-third is casein and two-thirds lactalbumin. 

 > Meigs and Marsh give the following table as representative of the 



