MILK BEFORE DELIVERY. 47 



the sugar and casein corrected accordingly. But if it be required 

 to determine the salts with perfect accuracy, it is best to inci- 

 nerate a weighed quantity of milk, and to analyse the residue. 

 The analyses of Clemm, 1 which will be presently noticed, 

 were made in the following manner : One portion of milk was 

 used for the determination of the water and of the solid residue, 

 and afterwards (by incineration) of the fixed salts. Another 

 portion was evaporated nearly to dryness, and treated with one 

 or two drops of acetic acid to coagulate the casein and render 

 it insoluble. It was then treated with ether, in order to remove 

 the fat, and with water in order to take up the sugar of milk, 

 extractive matters, and salts. The residue was regarded as 

 casein.] 



Healthy Milk. 

 1. Milk before delivery. 



The mammary glands secrete a milky fluid during pregnancy 

 which, at first, diifers considerably from normal milk, but, as 

 the period of delivery approaches, gradually approximates to it 

 in its characters. In the first stage of its secretion, albumen 

 preponderates, and sugar is almost entirely absent ; the albumen 

 gradually gives place to casein, and, at the same time, sugar 

 and fat are more abundantly formed. There are no means of 

 obtaining any very accurate information respecting the fluid 

 secreted in the breasts of women previous to childbirth, 2 but 

 experiments have been made by Lassaigne and myself on this 

 secretion in animals. 



I analysed the milk of an ass pregnant for the first time, and 

 within about fourteen days of her full period of gestation. 

 The fluid was transparent, scarcely opalescent, tenacious, and 

 viscid ; it had an alkaline reaction. The microscope revealed 

 a few fat-corpuscles, some granular bodies, composed of accu- 

 mulated minute fat-vesicles and mucus-corpuscles. 



It did not become more gelatinous or stringy on the addition 

 of caustic ammonia; when heated, a considerable quantity of 



1 The investigations of Cleram are contained in the article "Milch" by Scherer, 

 in Wagner's Handworterbuch der Physiologie, vol. 2, 1845. 



8 [Clemm found that the fluid obtained from the breasts of a woman shortly before 

 delivery contained 5'478g of solid constituents.] 



