226 



COLOSTRUM AND MILK. 



Properties of logical relations in nutrition. It may now be added that fresh 

 milk. milk presents an alkaline reaction, which continues longer in 



the milk of women than in that of cows. Left to itself, and the more 

 quickly the warmer the air, milk turns sour through the production of 

 lactic acid, the casein undergoing coagulation. That the oil globules just 

 spoken of are coated with a film of a coagulated protein body appears 

 from the circumstance that it may be dissolved by acetic acid, and the in- 

 cluded butter is then set free. 



One of the simplest methods for the analysis of milk consists in coag- 

 Anaiysis of ulating it at a temperature of 212 with pulverized gypsum ; 

 milk - the mass, being then evaporated to dryness, is pulverized, the 

 butter being extracted by ether, and the sugar and soluble salts by hot 

 alcohol. * The amount of the soluble salts thus obtained may be determ- 

 ined by incineration ; and since their amount is to that of the insoluble 

 salts as 5 to 7, an approximate determination of the latter may be made, 

 and thereby the weight of the sugar and casein corrected. This is the 

 method of Haidlen. 



It would appear, from examinations that have been made of the secre- 

 T> i * f tion of the mammary gland previous to parturition, that it 

 lostrum and contains albumen in the place of casein, the casein gradually 

 appearing as the period of parturition approaches, but not 

 reaching its maximum until a few days after that event. Colostral milk 

 differs essentially from the subsequent ordinary secretion, as the follow- 

 ing table shows : 



Constitution of Colostrum and Milk. (From Simon.') 



The specimens here presented were obtained from the same individual ; 

 and from the table it appears that the colostrum contains a much larger 

 proportion of solid material than the milk. The quantity of fat is near- 

 ly double ; the quantity of sugar is likewise much greater, but the rela- 

 tive quantity of casein is less, this being in accordance with the state- 

 ment that the production of that substance approaches gradually to a 

 maximum which is not attained till a few days after parturition. 



The composition of milk varies with many circumstances. Thus, 

 Variability in among cows, it is well known that there are certain breeds 

 its composition. w hi c h yi^a a m $k { n wn i c h butter predominates ; in others, 

 a milk in which there is an excess of casein. It is in reference to this 

 that such are, among agricultural people, often described as good butter 



