DAIRY FARMING DAIRYING. 285 



The results of investigations on this subject, especially those of 

 Michaelis, are summarized by the author as follows : 



(1) The epithelium of the mammary glands is composed of only one 

 layer. 



(2) The fat of milk is a true product of secretion — a product of the 

 life activity of the cells and not a product of their degeneration. 



(3) At the present time nothing definite can be said regarding the 

 method of secretion of milk sugar. 



(4) Casein is a compound product, derived partly from albuminoid 

 bodies produced by the excreting epithelial cells, and partly from the 

 disintegrated nuclei of these cells. The nuclein of milk is derived from 

 the latter source. 



(5) The fat globules are not inclosed in a membraue. 



(6) The colostrum bodies originate from large, mononuclear leuco- 

 cytes, capable of amoeboid motion. These bodies reappear in the invo- 

 lution period of the glands. The leucocytes take no part in the pro- 

 duction of milk, and the poly nuclear ones disappear; but during ges- 

 tation, immediately after birth, and for a short period after weaning, 

 they pass through the epithelium in all forms and in great numbers. 



(7) During lactation large quantities of free epithelial nuclei are 

 found in the lumen of the alveoli, which decompose and assist in form- 

 ing an integral constituent of the milk, namely, the casein. 



(8) The pressure of the secretion in the alveoli may flatten the 

 cubical cells, but at certain stages the cells of the mammary glands are 

 papilliform. The latter condition is not due to the stage of fullness 

 of the lumen, but indicates an independent change of form in the 

 epithelium during lactation. 



Analyses of milk, A. L. Winton, A. W. Ogden, and W. L. Mitch- 

 ell {Connecticut State Sta. Rpt. 1897, pp. 321, 322). — Analyses are 

 reported of the mixed milk of 6 cows on the last day of each of 4 periods 

 of 2 weeks' duration on different feeds. The feeding was not done at 

 the station, but the samples were sent for analysis. In the first and 

 third periods the cows were fed cut-corn fodder, hay and corn silage 

 with a mixture of wheat bran and cotton-seed meal, 1:1. In the 

 second and fourth periods the coarse fodder remained the same, but 

 wheat bran and Cleveland linseed meal 1:1 were substituted for bran 

 and cotton seed meal in the proportion of 3 qt. to 2. During the 

 linseed-meal periods the milk contained somewhat less fat and more 

 water than during .the other periods. No data are given as to the 

 yield of milk. 



Analyses of some California creamery butters, M. E. Jaffa 

 [California Sta. Rpt. 1895-1897, pp. 116-120). — In order to compare Cali- 

 fornia butter with premium butter from the American Dairy Show at 

 Chicago, analyses were made of G samples of creamery butter from the 

 bay region and 6 from Humboldt County. In addition, samples of 



