EFFECT OF FOOD UPON THE QUALITY OF MILK. 



WHAT IS MILK f 



This question is an old one, but nevertheless no complete answer 

 has been given to it, nor can one be given to-day. Certain things 

 are known to be true concerning milk, and from the works of physi- 

 ologists, chemists and microscopists we are able to give something of 

 an answer to this question. We inay study milk in two ways, with 

 the microscope, and with the apparatus of the chemist. 



1st. How does milk appear when viewed under the microscope? 

 Not as a simple white fluid as it does to the naked eye, but as a fluid 

 in which are floating countless millions of little spherical particles ; 

 these are the fat globules, little droplets of pure butter fat. These 

 vary very much in size, botti in individuals and among breeds ; the 

 average figures resulting from" measurements of our four breeds, 

 namely: Jersey, Holstein, Ayrshire and Shorthorn, have been found 

 to be about one eight-thousandth of an inch. If we would get some 

 idea of how small a particle this is, let us remember that such a 

 globule under a microscope magnifying 500 diameters would appear 

 one sixteenth of an inch in diameter, while a common lead pencil 

 magnified the same number of times would appear fifteen feet in 

 diameter ; or, if we should desire to lay a row of these little particles 

 of fat across the squared end of the pencil, it would require 2,500 

 of them, or to cover the entire surface of the pencil end would require 

 4,900,000 globules. 



That the globules vary in size has already been alluded to. Glob- 

 ules are found that are only one forty-thousandth of an inch in 

 diameter, and others one twenty-five-hundredth of an inch. 



THE CHEMICAL COMPOSITION OF MILK. 



The common method of analyzing milk, separates the sample into 

 five parts, namely : water, fat, caseine, sugar and ash. This compo- 

 sition varies greatly, both among individual animals of the same breed, 

 and also the averages of breeds. I have selected two animals, one 

 a Jersey, the other a Shorthorn, to show the variation of each constitu- 

 ent of the milk, and also have given the average per cent, of fat in 

 the milk of each cow, as well as the fat in the milk of each breed. 



