THE COLOSTRUM. 417 



ing the lactose crystallizes out. To purify the substance, this is dis- 

 solved in water, decolorized with animal charcoal, and recry stall ized 

 by evaporation. It is thus obtained in the form of white rhombic 

 prisms, which are soluble in water, but insoluble in absolute alcohol. 

 The substance has a somewhat sweetish taste, and contains one mole- 

 cule of water of crystallization, which rapidly escapes at 130 C. 



Estimation. To estimate the amount of lactose, the milk must 

 first be freed from fats and albumins. To this end, it is most con- 

 venient to dilute with water and to remove the casein by the cau- 

 tious addition of acetic acid. The resulting precipitate, which 

 contains both the casei'n and the fat, is filtered off and the filtrate 

 boiled. After the removal of the precipitated coagulablc albumins, 

 the sugar is then estimated in the filtrate by titrating with Knapp's 

 solution, as described in the section on the Urine. Ten c.c. of the 

 reagent correspond to 0.031 gramme of lactose, providing that the 

 solution contains from 0.5 to 1 per cent, of sugar. 



In addition to lactose, the milk contains also small amounts of a 

 reducing substance, which is supposedly identical with Landwehr's 

 animal gum. It is possible, however, that, as in the case of the 

 reducing substances of the mucins and mucoids, chondroitin-sul- 

 pliuric acid or an allied substance may be responsible for the 

 reactions. 



Extractives. Among the extractives of the milk, which com- 

 prise traces of urea, kreatin, kreatinin, xanthin-bases, lecithins, 

 cholesterin, and citric acid, the latter is of especial interest, as it 

 is apparently also formed in the mammary glands, and is not refer- 

 able to the ingestion of the substance as such. It has been found in 

 human milk as well as in cows j milk, and is notably present in com- 

 bination with calcium. Its amount in cows' milk is given as 0.25 

 per cent., while in human milk a somewhat smaller quantity occurs. 



The formula of the acid is CH 2 .COOH.C(OH).COOH.CH 2 . 

 COOH, viz., C 6 H 8 O 7 ; it is thus oxy-propon-tricarbonic acid. 



Colostrum. 



The term colostrum is applied to the secretion of the mammary 

 glands which is furnished by the female animal during the fir<t 

 days of lactation, and which may also be expressed from the glands 

 during a variable period preceding parturition. 



On microscopical examination such fluid is seen to contain innum- 

 erable fat-globules, and in addition a variable number of granular 

 cells, which are capable of manifesting amoeboid movements. These 

 are termed colostrum-corpuscles, and are commonly regarded as 

 leucocytes. This, however, is doubtful. According to Woodward, 

 they have a small irregular, but much degenerated nucleus. Of the 

 granules, a few are stained by osmic acid, while none of them takes 

 up either acid, neutral, or basic dyes. In their reactions they show 

 the characteristics of proteid material. 



27 



