ITS CHEMICAL CONSTITUENTS. 337 



to 7'OOJ of milk-sugar in the brunette, and 1*00 and -95 of 

 casein; and from 5'85 to 6'40-jf of sugar of milk in the blonde. 



Peligot made the striking observation, which has recently been 

 confirmed by Reiset,* that the milk which is last yielded during 

 milking or artificial suction, is much richer in fat than that which 

 is first drawn, although the composition of both portions is other- 

 wise the same. It was supposed from these observations, which 

 were at first limited to the ass and the cow, that the milk lost some 

 portion of its cream in the mammary glands, while the more 

 watery and less fatty milk collected in the lower part of the udder; 

 but as Reiset has made the same observations in respect to 

 women's milk, which had been drawn in fractional portions from 

 the breast, the cause can scarcely be dependent upon such simple 

 mechanical relations as these. 



Peligot found 6*45^ of butter in the first third of the milk of 

 an ass, 6'48-J in the second, and 6*50J in the last portion. Reiset 

 found precisely similar relations in the milk of two cows, pro- 

 vided a full period of four hours had intervened between both 

 times of milking ; for when the animals were milked after 

 intervals of two hours only, there was no perceptible difference in 

 the various portions of one and the same milking. When the 

 collective milk of a cow yielded 4 5-g- of fat, the last portions of the 

 milk were found to contain 7*63, 7*53, and S'40% of butter. The 

 milk of a nurse, aged 27 years (seven months after delivery), 

 yielded more fat after the child had drawn the breast (on an 

 average 5*54^) than before its application (on an average 3'24-g-). 



According to Simon's investigations, the quantity of fat con- 

 tained in woman's milk remains nearly the same throughout the 

 entire period of lactation. 



The nature of the food affects, at least in some degree, the 

 quantity of fat contained in the milk. Boussingaultf found that 

 cows fed upon carrots, without the leaves of the plant, yielded 

 milk containing 1'25 of fat, while the milk contained only 1'4 of 

 butter when the food consisted of oats and lucerne. Playfair 

 thought he could perceive an increase in the quantity of butter in 

 the milk when the cows were fed on potatoes. The result of 

 experiments made by Boussingaultt on two cows was as follows : 

 after feeding the animals on beet-root, the milk of one cow was 

 found to contain 4'56-g, and that of the other 3'42-g of fat; when 



* Ann. de Chim. et de Phys. 3 S^r. T. 25, p. 8285. 

 t Ibid. T. 11, p. 433. 

 t Ibid. T. 12, p. 153. 

 VOL. II. Z 



