MILK 



The Formation of Milk. The exact method in 

 which milk is formed in the udder is, as yet, far from 

 having been clearly demonstrated. Two important 

 theories have been advanced. According to the 

 older one, which held sway in scientific circles up to 

 the year 1840, milk is formed directly from the 

 blood it is, in fact, a sort of filtered blood. Accord- 



FIG. 5. UNCONNECTED EPITHELIAL CELLS. 

 Magnified 600 times, b, Protuberance rest- 

 ing on basement membrane ; /, nucleus. 

 (Flirstenberg.) 



FIG. 6. EPITHELIAL CELLS. 

 Magnified 600 times, a, 

 Attached together ; b, 

 free cell. (Fiirstenberg.) 



ing to this theory, the milk-glands merely act as a 

 filter. The other theory regards milk as the product 

 of the decomposition of the epithelial cells. There 

 can be no doubt which of these two theories com- 

 mands most support from the data available. In the 

 first place, if milk be merely filtered blood, its 

 quantity and quality will be directly influenced by 

 the food of the cow. That this is not so, practical 

 men have long known. No doubt food has a certain 



