CHAP, iv. COLOSTRUM, 287 



from the debris of the central cells of the alveoli, and the presence of 

 this animal matter must seriously interfere with the ripening of the 

 cheese. The percentage of this material is, of course, largest at first, 

 and steadily diminishes. 



Colostrum is denned by Dr. Meade Smith, in his " Physiology of the 

 Domestic Animals," as an opaque, yellowish fluid, containing a large 

 amount of the so-called colostrum cells (true glandular cells in different 

 stages of fatty degeneration), few milk globules, a large amount of 

 albumin, little or no casein, and but little fat, milk-sugar, and salts. 

 On account of its large percentage of albumin it coagulates when 



Fig. 70. Microscopic appearance of (i) Milk, (ii) Cream, (iii) Butter, 

 (iv) Colostrum of Mare, (v) Colostrum of Cow (Thanho/er}. 



heated, differing in this respect from milk ; in fact, colostrum when first 

 secreted closely resembles blood-serum, with the addition of colostrum 

 corpuscles. Gradually, however, the colostrum secretion passes into 

 a milk secretion ; albumin and colostrum corpuscles become reduced in 

 quantity ; fat, casein, sugar, and milk-globules increase. The specific 

 gravity of colostrum varies from 1040 to 1060, being higher imme- 

 diately after delivery, and falling as it gives place to a true milk secre- 

 tion. The reaction of colostrum is ordinarily alkaline, and becomes 

 acid on standing. Immediately after calving, the colostrum of the cow 

 contains 8'5 per cent, of albumin, after one day 6'4 per cent., after 

 three days 3*4 per cent., after seven days 1'9 per cent., and after twenty- 

 one days 0'6 per cent. On an average colostrum may be said to have 

 the following composition : - 



