MILK. 391 



great occasions. Yet the natives of the Tonga Islands think 

 that nothing can be more disgusting than for a human being 

 to drink the milk of a cow. 



How the operation of milking is conducted we need not say, 

 whether it be performed on the cow as with most nations, or 

 the ass in case of need with ourselves, or the mare as with 

 the Tartars, or the goat and sheep in various parts of the 

 world. The milk of the sheep, by the way, is singularly rich 

 and nourishing. 



Suffice it to say that the animals which are to be milked are 

 kept for that purpose, and that the touch of the human hand, 

 rightly applied, induces the animal to part with its milky stores. 



In Nature there is an exact parallel. 



It has long been known that some species of Ants are in 



ANT AND APHI8- MILKING COW. 



the habit of acting in exactly the same manner as ourselves, in 

 not only extracting a nutritious liquid from other insects, but 

 watching and tending those which furnish their daily food just 

 as a good dairyman watches and tends his cows. 



The Ants, being insects, would naturally require insect cows, 

 and such are to be found in the Aphides, of which mention has 

 already been made. These insects are furnished with a pair of 

 very small tubercles near the end of the abdomen, and from 

 them flows that sweet liquid which is so familiar to us under 

 the name of "honey-dew." For centuries no one knew the 

 source of the sweet honey-dew which attracted all the bees of 

 the neighbourhood to the tree on whose leaves it was sprinkled, 

 sometimes in patches, and sometimes coating them with a thin 

 shining coat, as if varnished. 



At last it was discovered that the honey- dew is, in fact, the 



