THE FOOD VALUES OP MILK 407 



fat in the finished body bore a constant relation to the ratio of pro- 

 teins to fat, or fat forming compounds in the material consumed. 

 Milk varies in composition, not alone in fat but in every 

 other component. The natural milk containing the lowest per 

 cent of fat, has also the lowest amount of fat in proportion to 

 the other solid food substances in the milk. Such milk also has 

 the highest percentage amount of ash in the solid food matter, 

 while the richest milk, not only has the largest amount of fat 

 in the liquid milk, but the largest proportion of fat to total 

 solids in the solid food substances of the milk. For instance, a 

 3 per cent fat milk has 6*/o per cent ash in the solids, while a 

 6 per cent milk has only 4% per cent ash in the solids. A 3 per 

 cent milk has only 27 per cent of fat in the solids, while the 

 solid matter of a 6 per cent milk is nearly 39.0 per cent fat. 

 Skim milk and buttermilk are essentially liquid lean meat. 



Percentage Composition of Water- free Substance in Milk of Varying 

 Fat Content 



This relation is better illustrated by Fig. 131. There is 

 danger in the nation-wide habit of feeding young, growing child- 

 ren "top milk." This is simply thin cream and is desperately 

 lacking in bone and muscle building substances and is too rich 

 in the heating and adipose forming elements. The relation 

 between food and bodily condition is best illustrated by the 

 following summary of tests made by the author in the University 

 of Vermont, and reported in Bulletin 195. 



