640 
The colostrum corpuscles are very abundant during the first few 
days, but under normal conditions disappear after the tenth or 
twelfth day. 
Function of colostrum. — The exact role of the colostrum is not as 
yet fully understood. We may infer from the nature of its composi- 
tion and its proteids that it furnishes to the newborn child during its 
adjustment to its novel surroundings the full expansion of the lungs 
and the awakening of the digestive processes, nourishment of a char- 
acter similar to that it received from the placenta as a fetus. That it 
serves a purpose is proven by its being the first secretion not only of 
the human breast but of that of all mammals. 
Physical characteristics of woman’s milk. — With the establishment 
of lactation the breast secretes a fluid of the following physical char- 
acteristics : It is of a bluish color and marked sweetish taste. Under 
normal conditions, with the exception of some skin cocci, it is practi- 
cally sterile. These are most abundant in the “ foremilk.” Its 
specific gravity varies from 1.026 to 1.036 (average, 1.032 at 21° C.). 
Its reaction is either amphoteric or slightly alkaline when fresh. 
Dilute acetic acid merely produces a light flocculent precipitate, and 
its proteids are not appreciably coagulated by the action of rennet. 
C omposition. — The exact average composition of breast milk is 
difficult to determine, as it is subject to rather wide variations between 
normal limits and at different stages during the act of being secreted. 
Thus the “ foremilk ” is relatively thin, the middle portion richer, and 
the “ strippings ” richest of all in fat content. Owing, moreover, to 
faulty methods, previous analyses of woman’s milk have been erro- 
neous. Even now its exact composition, beyond the relative propor- 
tions of its constituents, is imperfectly understood. 
According to the most recent analyses of Pfeiffer, Koenig, Leeds, 
Harrington, Adriance, and others the average composition of human 
milk is as follows : 
Composition of woman’s milk. 
I 
Percent- 
age. 
Common nor- 
mal varia- 
tions. 
Per cent. 
Fat _____ ___ _ _ _ _____ 
4.00 
3.00- 5.00 
Sugar. ’ _ _ _ _ . 
7.00 
6.00- 7.00 
Proteids 
1.50 
1.00- 2.25 
Salts.. _ _ _ 
.20 
.18- .25 
Water. _ 
87.30 
89.82- 85.50 
100.00 
100.00 100.00 
An average calorie value per kilogram, 710.5 calories ; common normal variations of 
caloric value per kilogram, 550 calories to 844.25 calories. 
