294 THE FORMATION OF MILK FAT 



THE FORMATION OF MILK FAT 



The fat appears in the cells of the mammary glands in the form 

 of minute droplets, as may be seen in osmic preparations. These 

 droplets run together and approach the free edge of the cell. 

 Heidenhain supposed that the front edge of the cells broke down 

 and thus set free the fat ; this is denied by Benda, who finds no 

 sign of a torn cell wall in his preparations of active gland. The 

 cell actively produces fat it is not a product of regressive meta- 

 morphosis or fatty degeneration (Bezzozero and Benda). 



Voit regarded the milk fat as a decomposition product of body 

 and food proteid, Soxhlet and others as a product of food and 

 body fat, while still others ascribed its origin partly to carbo- 

 hydrate. Voit, feeding a bitch on lean meat, came to the conclusion 

 that it put on more fat and separated more butter in the milk than 

 was in the food. 1 From metabolic researches both on the bitch 

 and cow he concluded that the proteid in the food sufficed to 

 produce all the fat in the milk. He supposed that the mammary 

 cell substance decomposes into milk and is re-formed, that proteid 

 is essential for rebuilding the cell substance, and that carbohydrate 

 and fat act only as proteid sparers. While the earlier investigators 

 found no effect on the milk on feeding fat, but bettered the 

 quality by giving more proteid, the more recent workers have un- 

 doubtedly influenced the milk by increasing the fat in the food. 



Thus Stohmann observed the favourable effect of feeding oil 

 to a goat, and the lessening of the yield of butter on removing fat 

 from the diet. The melting-point of the butter has been found 

 affected by the feeding of cotton-oil, palm-oil, and cocoa butter. 

 Rosenfeld, by constantly feeding bitches with mutton fat, caused this 

 fat to accumulate in the fat depots, and the animals produced a 

 butter with the iodine number of mutton fat. Henriquez and 

 Hansen found feeding cows with linseed - oil raised the iodine 

 number in milk fat from 30 up to 59*7 and even to 70'4, showing 

 the increased proportion of olein. Stellwaag found that cows fed 

 on a mash of maize gave a butter too low in melting-point to be 

 marketable. Oil-cake fed to cows produces an oily milk. Baumerfc 

 and Falke fed sesame and almond oil, and found the milk fat to 

 consist of a mixture of butter fats with these foreign fats. Winter- 



1 The possible errors in Voit's researches have been considered above. 



