338 



HANDBOOK OF PHYSIOLOGY. 



ordinary molecular movements. The milk which is secreted in the first 

 few days after parturition, and which is called the colostrum, differs from 

 ordinary milk in containing a larger quantity of solid matter; and under 

 the microscope are to be seen certain granular masses called colostrum- 

 corpuscles. These, which appear to be small masses of albuminous and 

 oily matter, are probably secreting cells of the gland, either in a state of 

 fatty degeneration, or old cells which in their attempt at secretion under 

 the new circumstances of active need of milk, are filled with oily matter; 

 which, however, being unable to discharge, they are themselves shed 

 bodily to make room for their successors. Colostrum-corpuscles have 

 been seen to exhibit contractile movements and to squeeze out drops of 

 oil from their interior. 



Chemical Composition. In addition to the oil existing in numberless 

 little globules, coated with a thin layer of albuminous matter, floating 



FIG. 230. Globules and molecules of Cow's milk, x 400. 



in a large quantity of water, milk contains casein, serum-albumin , milk- 

 sugar (lactose), and several salts. Its percentage composition has been 

 already mentioned, but may be here repeated. Its reaction is alkaline: 

 its specific gravity about 1030. 



Table of the Chemical Composition of Milk. 



Water, 

 Solids, 



Proteids, including Casein 

 and Serum-Albumin, . 

 Fats or Butter, 

 Sugar (with extractives), 



Human. 

 890 

 110 



1000 

 Human, 



35 

 25 



48 



Cow. 

 858 

 142 



1000 

 Cow. 



68 

 38 

 30 



