48 THE COMMON SENSE OF THE MILK QUESTION 



for of course the milk must contain proper nourish- 

 ment for the young of the animal producing it, and 

 we could not expect that the same kind of nourish- 

 ment would do for a kitten and a young elephant; 

 that the food intended by Nature for a young porpoise 

 would suit the stomach and nutritional needs of a 

 human infant. 



But before we proceed to examine the constituents 

 of the milk of various animals we must consider 

 carefully a most significant fact. In the preceding 

 chapter it was pointed out that there are many im- 

 portant variations in the composition of the milk 

 of women. Not only are there differences in the 

 milk of a woman at various stages of her baby's 

 growth, but one woman's milk at a given period of 

 lactation will frequently differ in marked degree 

 from the milk of another woman at the same period 

 of lactation. We also observed that cow's milk is 

 subject to much the same variation. Not only do 

 the various breeds differ in this respect, but the milk 

 of one cow is frequently much richer than the milk 

 of another cow of the same breed in the same herd.' 

 It will be readily understood, therefore, that a good 

 deal of latitude has to be allowed if we are to talk 

 of the "average" composition of any kind of milk. 

 The table which follows is probably as satisfactory 

 as any that could be compiled, but it is only one chosen 

 from among a large number in which there are more 



