HUMAN MILK. 
127 
Under the influence of extracts of the pancreas, the caseinogen, 
before it is clotted by the tnilk-curdling ferment of the gland, p 
through ;i stage in which it coagulates by heat. This was termed 
the " metacasein " reaction by its discoverer, Sir William Roberts. 1 It 
does not appear to be due to the simultaneous developmenl of acid 
produced by the fat-splitting Eermenl of the pancreas, bul rather to 
the action of trypsin. Edkins 2 showed thai Kiihne's purified trypsin 
also produces "metacasein" in an early Btage of its action, though it 
does not produce coagulation of milk. 
The composition of milk varies in different animals; human milk 
and cows' milk" arc those which have been most investigated. There 
are also variations due t<> constitution, state of nutrition, and age. 
Human rnilk. — -The mammary glands of new-born animals of both 
sexes often secrete a small quantity of milk for a few days. It is 
popularly termed "vritcTies' mill-." It is alkaline. 3 Analyses by Schloss- 
berger and Hauff, 4 (rubier and Quevenne, 5 and Genser, 8 show that the 
milk of new-born children contains from l'Oo to 2'8 proteid, - 82 to 
1-46 fat, - 9 to 6'4 sugar, and 0*8 salts per cent. 
Colostrum. — This liquid is yellower and more alkaline than fully- 
formed milk. It contains colostrum corpuscles, rather more solids than 
milk, and coagulates on heating. It contains little or no caseinogen, 
but a mixture of lacto-globulin and lactalbumin. 7 The globulin is only 
present in traces in fully-formed milk. The following analyses are by 
< llemm, 8 with the exception of the last, which is by Tidy. 
Constituents. 
Four Wee 
Deli 
I. 
ks before 
\ ery. 
II. 
Seventeen 
Days before 
Delivery. 
Nine Days 
before 
Delivery. 
Twenty- 
four Hours 
after 
Delivery. 
Two Days 
after 
Delivery. 
Water 
94-52 
85-2 
85-17 
85-85 
84-38 
8679 
81-08 
Solids . 
5-18 
14-8 
14-83 
14-15 
15-02 
13-21 
15-92 
Casein 
2-18^ 
Albumin and 
2-88 
6-9 
748 
8-07 
~} 
3-23 
globulin 
Fat . 
0-71 
4-1 
3-02 
2-35 
4-86 
5-78 
Lactose 
1-73 
3-9 
1-37 
3-64 
6-10 
6-51 
Salts . 
0-44 
041 
0-45 
0-54 
0-51 
0-31 
1 Proc. Roy. Soc. London, 1879, 1891. 
- Journ. Physiol., Cambridge and London, 1891, vol. xii. p. 203. 
3 Witches' milk obtained from foals by Amnion (Jahresb. it. d. Fortschr. d. Thier-Ghem , 
Wiesbaden, 1876, S. 118) was acid, but this was probably due to fermentation having set in. 
4 Ann. d. Chan., Leipzig. Bd. xcvi. S. 68. 
5 Gaz. med. de Paris, 1856, p. 15. 
sjahrb.f. Kvnderh., Leipzig. N. F., Bd. ix. S. 60. 
7 J. Sebelien, Ztschr. f. physiol. Ohem., Strassburg, Bd. xiii. S. 135. 
' Wagner's " Handworterbuch d. Physiol," Bd. ii. S. 464. 
9 Lond. Hosjh Re})-, 1867-8, p. 77. See also Woodward {Journ. Exper. Med., Baltimore, 
1897, vol. ii. p. 217), for recent analyses of human colostrum. Colostrum corpuscles are 
not constantly present. 
