44 



THE NORMAL COMPOSITION OF MILK 



It was found that the size of the globules at the commence- 

 ment of lactation was about twice the average size for the whole 

 period; the size sharply diminished during the first six weeks 

 and then, after remaining fairly constant for some months, 

 rapidly declined. The iodine value varied directly with the 

 fat content, and the saponification value, after a preliminary 

 rise, declined slowly, but gradually, with the constantly decreas- 

 ing proportion of volatile fatty acids. The melting point 

 remained comparatively steady until the last periods when a 

 perceptible rise occurred; the refractive index showed no appre- 

 . ciable variations. 



Non-fatty Solids. The non-fatty solids of milk are subject 

 to variations from causes similar to those which determine 

 the variation in the fat content. The influence of breed is 

 shown in Tables XIII, XIV, and XV, and that of season in 

 Table XIX (Richmond '^). 



Table XIX 

 INFLUENCE OF SEASON ON SOLIDS-NOT-FAT 



Month. 



January. . . 

 February. . 

 March . . . 



April 



May 



June 



July 



August. . . 

 September, 

 October . . 

 November. 

 December . 



Ash. 



0.76 

 0.75 

 0.74 

 0.75 

 0.74 

 0.74 

 0.75 

 0.71 

 0.74 

 0.75 

 0.76 

 0.75 



These results show that the solids-not-fat decline sympa- 

 thetically with the fat during the spring and summer months, 



