650 Effect of Food on Milk Production, [nov., 



ing of cows can exert only a very limited effect on the com- 

 position of the milk produced. He pointed out, in the first 

 place, that the materials entering the milk gland from the 

 blood and lymph vessels become, first of all, an integral part of 

 the gland cells, and the milk is produced only by the disinteg- 

 ration of these gland cells, which are constantly regenerated. 

 These animal organs are fairly steady in their composition, 

 and are not able to utilise foreign substances for building-up 

 purposes, so that the decomposition of the milk gland can 

 only result in a product having slight variations. This com- 

 parative constancy in composition is a natural necessity in 

 view of the needs of the calf for whom the milk is intended. 



If the composition of the food of a cow exerted any essen- 

 tial influence upon the ingredients of the milk, it might 

 happen, taking into account the various foods which are at 

 the disposal of wild animals, that a milk, rich in protein but 

 poor in milk sugar, would be produced one day, and the next 

 a milk poor in protein and rich in milk sugar. Such varia- 

 tions would be very injurious to the health and development 

 of the new-born animal and would render the continuation of 

 the species precarious. 



A similar argument applies to the amount of milk secreted. 

 If the quantity depended upon the nourishment taken, the 

 milk at the disposal of the young, in the case of animals 

 living in the natural state, would be subject to great varia- 

 tions, a circumstance which would not be to the benefit of the 

 progeny. 



The uniformity of the milk is secured by the fact that 

 it is not merely separated from the food materials in a 

 mechanical way, but that between the fodder of the mother 

 animal and the milk-forming organs a kind of regulator (the 

 body) comes into operation. If for the time being the fodder 

 is insufficient for the secretion of the proper quantity of 

 milk, the bodily substance of the mother fills the breach 

 caused by the missing food, and is drawn upon for the forma- 

 tion of milk until the body of the mother has become very 

 emaciated. Exactly the opposite process obtains if more be 

 given in the way of fodder than the mother animal can 

 convert into milk. The superfluous matter is conserved in 

 the mother's body as a resource in time of need. This regula- 



