370 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



the fat of the milk when material rich in albuminoids, par- 

 ticularly palm-cake freed from oil, was added to the ration. 



Changes in the Milk during the Period of Lactation. 



The Moeckern experiments have also given more accurate 

 data upon this subject than have been ever before obtained. 

 In general, the total yield of milk decreases as the milking 

 period advances. The shrinkage is exaggerated by poor feed- 

 ing, and can be prevented in part by adequate food and con- 

 sequent maintenance of the body in good condition. The rich- 

 ness of the milk, the percentage of solids, increases. The 

 increase can be aided by proper feeding, and partly prevent- 

 ed by inadequate nourishment and consequent falling-off in 

 condition. As regards the changes in relative proportions of 

 solid matters, their ratios to each other, the proportion of fat 

 seems to decrease and that of casein to increase somewhat; 

 that of albumen diminishes, while the sugar remains constant. 



GENERAL CONCLUSIONS FROM EXPERIMENTS ON EFFECTS 

 OF FOOD UPON MILK PRODUCTION. 



Among the general principles deducible from the later ex- 

 perimenting on milk-production by cows, two of the weight- 

 iest are that of the food ingredients the most important as 

 factors of the milk-production are the albuminoids, and that 

 the production is controlled to a much greater extent than is 

 commonly supposed by the bodily condition. And these two 

 principles are, in fact, corollaries of the single, broader one de- 

 veloped by late research in this department of animal physi- 

 ology that the function of the lacteal glands is not entirely, 

 or even mainly, that of filters through which certain ingredi- 

 ents of the blood are secreted as milk, but that they them- 

 selves produce, by metamorphosis of their own substance, the 

 larger part of the solids of the milk; that, as Voit Bays, "the 

 milk is essentially this organ, liquefied by fatty degenera- 

 tion." It seems fairly well settled that all the casein and a 

 good part of the fat and sugar of the milk are products of 

 metamorphosis of the milk glands ; that of the fat and sugar 

 supplied by the blood, a portion results from similar metamor- 

 phoses in other parts of the body; and hence only a small 

 residue of fat and sugar can come directly from the food. 



