CHAP, iv.] METABOLIC PROCESSES OF THE BODY. 819 



The quantity of milk secreted by a woman in twenty hours 

 at the height of lactation has been calculated at 700 to 800 cc. 

 A good milch cow will yield about 10 litres of milk per diem. 



514. Colostrum. This is the name given to the milk 

 secreted at the beginning of a period of lactation, just before 

 and for some days after parturition. This milk differs from the 

 subsequent milk in microscopical characters and in chemical 

 composition. 



When ordinary milk is examined under the microscope hardly 

 anything is seen besides the fat globules except a very few 

 imperfect cells or portions of cells consisting of cell-substance 

 more or less loaded with fat and containing sometimes a more or 

 less altered nucleus. A few minute granules, whose exact nature 

 is uncertain, are however also visible. 



Colostrum on the other hand contains a large number of cells 

 or corpuscles, which have been called 'colostrum corpuscles.' Some 

 of these closely resemble leucocytes, others are either cells of about 

 the same size, round or irregular, and possessing a nucleus, often 

 misshapen, or are merely portions of cell-substance without a 

 nucleus. In some of them the cell-substance is loaded with fat 

 globules, in others it is fairly free from fat. Some of these cells 

 appear to be undergoing disintegration ; some may at a favourable 

 temperature exhibit slow amoeboid movements, and must then at 

 least be regarded as living. 



Colostrum also differs from ordinary milk in containing not 

 only a large quantity of albumin (lactalbumin) but also a decided 

 amount of globulin. In consequence of this colostrum differs from 

 milk inasmuch as it is distinctly coagulated by heat. 



As stated above, during the rapid growth by which the gland 

 is enlarged preparatory to lactation, the alveoli are at first solid 

 masses of cells with little or no lumen, and a lumen is established 

 subsequently by the discharge of the central cells. It is usually 

 supposed that the cells so discharged, some undergoing much, 

 others comparatively little change, supply the colostrum corpuscles 

 just spoken of, and at the same time furnish the globulin and 

 excess of albumin also characteristic of colostrum. But this is not 

 certain. The alveoli at this time contain peculiar cells resembling 

 colostrum corpuscles except that they are free from fat ; and it 

 is suggested that these being discharged and taking up fat in 

 amoeboid fashion become colostrum corpuscles. Some regard the 

 colostrum corpuscles as simply leucocytes which have similarly 

 taken up fat. 



515. The mammary gland is present both in the female 

 and the male child at birth ; and in both sexes at and for a few 

 days after birth is thrown, in common with all the other secreting 

 glands, into secretory activity, and a small quantity of milk, the 

 " witches' milk ". so called by the Germans, is discharged from the 

 nipple. This milk resembles in all essential features the milk of 



