14 MILK HYGIENE 



stage, there was a pouring out and solution of this 

 part of the cell, that the fat globules were transformed 

 into milk globules and the albuminous part of the cell 

 protoplasm became part of the milk fluid and that the 

 remaining portion of the cell, with the nucleus, was soon 

 regenerated, whereupon a fatty degeneration again oc- 

 curred in the regenerated portion of the cell. Eecently, 

 doubts have arisen as to whether, during the production 

 of milk, there is, after all, a material disintegration of 

 the cell protoplasm. Ottolenghis 's investigations appear 

 to show clearly that milk secretion is an active cell 

 process precisely as other secretions are, and that it 

 does not depend upon the destruction of the cell. The 

 destruction of entire cells and their elimination appears 

 to occur only to a limited degree, but the presence of 

 karyokinetic figures shows that, here and there, in the 

 gland, such a disintegration does occur with consequent 

 reproduction. 



The milk from animals of different species contains 

 the same ingredients, namely: water, albuminoids (es- 

 pecially casein and albumin), milk sugar (lactose), fats 

 and inorganic salts. In regard to quantitative compo- 

 sition, there are marked differences between the milks 

 of animals of different species. 



Among the ingredients of milk it is supposed that 

 casein is the direct product of the gland tissue, globulin 

 of the broken down parts of cells, while it is not known 

 whether albumin originates at the same source or comes 

 from the blood. Concerning the origin of lactose, there 

 are different opinions. Some investigators suppose this 

 material is formed in the liver from glycogen or related 

 materials, while others think, and indeed with reason, 

 that it is formed in the udder by synthetic building up 

 of glucose and galactose. The latter cannot, as such, 

 have been taken up with the food, but must have been 



