794 DEVELOPMENT 



The secretion of the first few days is called the colostrum. It contains a 

 larger per cent, of solids, has the large granular colostral corpuscles, is more 

 alkaline than ordinary milk, and has a specific gravity of 1040 to 1046. 



The mammary glands have been isolated from the nervous system to 

 determine whether or not the association in time between their changes and 

 the changes in the uterus were of a nervous nature. The isolated mammae 

 develop and begin lactation at parturition as in the normal. It would seem 

 that there is some special form of stimulation through the medium of the 

 blood, i.e., by the hormones as suggested in the preceding paragraph. Yet 

 one must not draw the conclusion that the nervous system exerts no influence 

 on the mammary gland. Stimulation of the nerves to the gland produces 

 vascular changes that increase or decrease the quantity of milk secreted. 

 Many observations have been noted in women, which show that the secretion 

 of milk is sharply influenced, or even completely suppressed by nervous states. 



The Composition of Milk. Milk has a specific gravity of 1028 to 

 1034. Its fat is held in emulsion. Under the microscope, it is found that 

 the milk globules vary in size, the majority being from 2 to 3^ in diameter. 

 The old view that they have an investing membrane of albuminous material 

 is now generally discarded. 



COMPOSITION OF COLOSTRUM (PFEIFFER). 



Proteins 5.71 



Fat 2 . 04 



Sugar 3.74 



Salts 0.28 



Water 88.23 



100.00 



SALTS IN WOMAN'S MILK (ROTCH). 



Calcium phosphate 23 . 87 



Calcium silicate 1.27 



Calcium sulphate 2.25 



Calcium carbonate 2.85 



Magnesium carbonate 3-77 



Potassium carbonate 23 .47 



Potassium sulphate 8.33 



Potassium chloride 12.05 



Sodium chloride 21.77 



Iron oxide and alumina o-37 



100.00 



In addition to the oil or butter fat, milk contains certain proteins, milk- 

 sugar, and several salts. Its percentage composition is given in the tables 

 appended. 



