THE SECRETION AND PROPERTIES OF MILK 1385 



course, be greater with strong, big children, and smaller with weakly 

 children : 



INCREASE 



DECREASE 



29th-32nd week 

 33rd-36th . 

 37th week 



916 grm. 

 909 



885 



COLOSTRUM. Before the secretion of true milk begins, the fluid 

 which is obtain 3d from the breast is known as colostrum. It may be 

 expressed from the breasts immediately after birth and is ingested by 

 the child during the first two days after birth. The colostrum is formed 

 only in slight quantities. It is an opalescent fluid, often somewhat 

 yellowish, containing fat globules, which, if the fluid be allowed to 

 stand, form a yellowish layer on the top. Under the microscope, in 

 addition to the fat globules, may be seen the so-called colostrum 

 corpuscles, which consist of multinucleated cells loaded with particles of 

 fat. They are probably leucocytes or phagocytes which have wandered 

 into the alveoli and have taken up fat globules. Some of the cor- 

 puscles may be desquamated secretory cells. Colostrum is distin- 

 guished from true milk by containing little or no caseinogen. It 

 contains about 3 per cent, of proteins, namely, lactalbumen and 

 lactoglobulin, which coagulate on boiling. Lactose and salts are 

 present in the same proportions as in ordinary milk. It is popularly 

 supposed to have a laxative effect on the child. 



PROPERTIES OF MILK 



Fully formed milk presents certain features which are common to 

 all mammals. These have been chiefly studied in the case of cows' 

 milk. We may therefore deal with the composition of cows' milk 

 and point out later in what respects human milk differs therefrom. 



