1 68 POPULAR SCIENCE MONTHLY 



Milk is at once the most important and the most perishable of all 

 food products. Fresh milk is the most perfect mechanical emulsion 

 known and contains roughly proteicls (albuminoid substances equiva- 

 lent in nature to the white of the egg) fat, in the form of minute 

 globules which are later represented as cream, milk sugar, certain 

 mineral salts and water. There is more or less fluctuation in the 

 proportion in which these substances appear in all milks, particularly 

 the milk of cows, owing chiefly to the development (in some instances 

 covering periods of many hundred years) of certain breeds of cattle, 

 possessing, among other qualities, certain characteristics as milk pro- 

 ducers. I say chiefly to the development of breeds, because repeated 

 experiments with various breeds have shown that it is not possible to 

 alter materially the proportion in which the various constituents of 

 milk appear in the milk of any given cow by any process of feeding yet 

 discovered. 



Improved methods of feeding increase the total quantity of the 

 output, but not materially the quality, and any attempt to force by 

 feeding an increase in the percentage of any one of the ingredients in 

 the milk (particularly the fat content) may increase slightly for a 

 short time such content, but it soon drops to the normal for each 

 cow, and the experimenter has run the risk of ruining the animal 

 experimented upon. 



A popular fallacy prevails which enshrines in the minds of the 

 uninformed the belief that milk having a large percentage of fat is 

 rich milk, and hence, the best milk. Milk rich in fat and the best 

 milk from both a physical and a chemical view are not synonymous 

 terms, either as a matter of domestic economy or as applied to its use 

 for infants. While all good milk must possess fat, the consideration of 

 the amount thereof from a nutritive standpoint is second to that of 

 the proteid content except in a certain few selected cases, which rarely 

 include babies or young children. 



Dr. J. A. Gilbert, writing in The Medical Record (New York), 



takes the view that this devotion to " rich " milk has no logical basis. 



In our earnest search after a fat milk, he says, we have probably gone 



too far. To quote from an editorial in The Hospital (London) which 



notes Dr. Gilbert's opinion appreciatively: 



The milk which is richest in cream is not, therefore, the most nutritious, 

 for the very simple reason that a rich milk is less easily digested and absorbed 

 than a milk in which the fat percentage is low. As far as its other constitu- 

 ents are concerned, a milk poor in fat is as valuable a food as a milk rich in fat. 



Owing, then, to ignorance or personal interest, recent discussion of 

 the milk problem throughout the land has revolved around the per- 

 centage of fat in milk and undue prominence has been given this phase 

 of the question. 



Protein is the most important nutritive content in all milks, and 



