36 THE MILK QUESTION 



fats, the principal of which are olein, palmitin, and stearin. 

 These are neutral triglycerides of the corresponding fatty 

 acids. Besides these are found the triglycerides of myrictic 

 acid and butyric and caprolic acids. The last two are vola- 

 tile and give to butter its characteristic odor and flavor. 

 Milk-fat also contains traces of triglycerides of other fatty 

 acids. The composition of the fat in various milks is sub- 

 ject to slight variation depending upon racial peculiarities 

 and also upon the composition of the food and other con- 

 ditions. 



The fat droplets in milk are very tiny and can only be 

 seen under the higher powers of the microscope. They 

 vary considerably in size, but the average diameter is quite 

 constant for each species. Thus the fat droplets from 

 Holstein cows are considerably smaller than the fat drop- 

 lets from Jerseys and Guernseys. It is as easy to distin- 

 guish Jersey milk from Holstein milk under the micro- 

 scope, by the size of the fat droplets, as it is to distinguish 

 these distinctive breeds in the herd. The fat droplets in the 

 milk from Ayrshires are intermediate between the Holstein 

 and the Jersey. The Guernsey is comparable with the 

 Jersey, while the Devon has very small globules. There is 

 no relation between the size of globules and the richness 

 of milk. These statements are based upon observations 

 made at the Vermont Experiment Station and published 

 in its twenty-fourth annual report. 



Although the milk of Holstein cows has a smaller percent- 

 age of fat than that of Jerseys and Guernseys, the small 

 size of the individual droplets is believed to have one ad- 

 vantage so far as infant ^feeding is concerned, for it is well 

 known that fat must be emulsified before it can be digested, 

 and a fine emulsion favors its digestion and assimilation. 

 All Holstein cows do not furnish a milk poor in butter-fat. 

 It is possible to obtain a milk from a Holstein herd (with- 

 out any red cows) having the legal amount of fat and 

 more. 



