48 THE MILK QUESTION 



time 1 of lactation, 

 milk." True milk is not present in the mammary glands 

 until two or four days after parturition and occasionally not 

 until the fifth day. 



The amount of colostrum is very small. When it is ob- 

 tained by slight suction it is light in color, watery, sometimes 

 cloudy, with white or yellowish opaque streaks or threads. 

 When larger quantities are pressed from the glands a slimy 

 yellowish or even brownish to reddish liquid is obtained. 

 Upon standing, the cream rises in colostrum as it does in 

 normal milk, but the yellow color of colostrum adheres to 

 the fat, and the cream layer of colostrum therefore has a 

 more decided color than normal milk. 



Colostrum corpuscles. Under the microscope a very large 

 number of cells are seen in colostrum. These for the most 

 part consist of the so-called "leucocytes"; rather, de- 

 squamated epithelial cells which are found in normal milk. 

 Scattered in among these cells are numerous large granular 

 bodies known as colostrum corpuscles. They vary greatly 

 in form and consist of cells which are filled with fat drops 

 and contain two or three small elongated nuclei. It is be- 

 lieved that colostrum corpuscles consist for the most part of 

 leucocytes which have left the blood capillaries and have 

 pressed their way through the glands. These particular 

 leucocytes are active phagocytes and soon become laden 

 with fat droplets. Some of the colostrum corpuscles pro- 

 bably represent altered or degenerated glandular epithe- 

 lium. 



Colostrum is specifically heavier than milk: its specific 

 gravity is 1040 to 1080 and it may be either acid or alkaline 

 in reaction. It is not so sweet as milk, but is rich in salts 

 and proteins. It contains little or no casein, but a high 

 percentage of the coagulable albumins, namely, lactal- 

 bumin and lactglobulin, so that upon heating it coagulates 

 into a solid mass. It contains about as much fat as true 

 milk. 



