Formation of Mtlk. 41 



come disorganized from inaction mider close coniine- 

 ment, and this contains albuminous matter. But it 

 hardly seems logical to suppose that such transformation 

 would be required if the fats of milk were derived from 

 the vegetable fats that are already formed arid supplied in 

 the feed. Other reasons why the very small proportion 

 of fats in the feed — we have seen the proportion stated at 

 -j-J-Q part — would not seem to be sufficient or available to 

 supply the fats of milk, consist in the fact that the veget- 

 able fats are required for developing heat in all the tissues, 

 which heat is set free in the tissues, and circulated in the 

 blood ; the vegetable fats in the feed contributing in this 

 way to maintain th» liquid condition of the blood, and its 

 normal temperature, the circulation of the blood depend- 

 ing upon the maintenance of its temperature, which also 

 prevents its coagulation. 



The ripening of cheese results from the proteids being 

 changed or transformed into fat, which at least shows that 

 fat is formed, as Lawes and Gilbert, of England, proved 

 in fattening pigs from substances which are not fat ; and 

 the formation of fat from other substances in the gland 

 follicles, by a peculiar vital process, takes place within the 

 fat-cells themselves. This process changes the proteids 

 into fat, the fat being formed into cells, or globules, which 

 multiply in number from the nutritive material of the ar- 

 tery blood. As they successively attain sufficient size, the 

 fat globules separate, becoming detached within the gland 

 follicles. 



To whiten the milk, certain fat-cells — there are several 

 kinds of fat — are emulsified by a juice secreted from the 

 artery blood of the follicles, the fatty solution thus formed 

 then mingling with the milk and whitening it. The but- 

 ter globules are composed of yellowish fat, similarly 

 formed, but of a different quality, and are not dissolved. 

 4 



