WHY cow's MILK? 47 



classified. But while all the mammals are milk- 

 producing animals, rearing their young to a state 

 of comparative independence upon the lacteal fluid 

 secreted by them in their mammary glands, the 

 milk which they produce varies greatly according' 

 to the variations in the animals themselves. The 

 differences in the appearance of the milk of differ- 

 ent species are not very great. Some kinds look a 

 little yellower than other kinds, or perhaps a Uttle 

 thicker, but in general the milk of all animals bears 

 a very noticeable resemblance. This is all the 

 more remarkable when we think of the great differ- 

 ences in the appearance of the animals themselves. 

 There is little likeness between a woman and a camel 

 or an elephant, and the contrast between the human 

 being and the porpoise is quite as marked. That 

 a cat's milk should closely resemble the milk of a 

 cow or reindeer in appearance is remarkable in view 

 of the absence of any likeness between the animals, 

 and, more especially, the great differences in food 

 and habits which characterize them. 



If, however, we make an analysis of the milks of 

 some of these animals to ascertain their chemical 

 constituents, and then compare them, we shall find 

 that there are much greater differences in the com- 

 position of the various kinds of milk than would be 

 supposed by one who judged them only by their 

 looks. This is what we should naturally expect, 



