USE OF MAN'S INSTRUMENTS. 439 



it may quite as truly be said as of man, ' Necessitate quodlibet 

 ielum utile est' (In necessity whatever avails is a useful 

 weapon). 



If, therefore, instruments fashioned by man present them- 

 selves, and are quite as serviceable as, or more suitable 

 than, the natural implements they would otherwise employ, 

 they substitute the artificial for the natural. Thus thrushes, 

 that usually break snail-shells against pet stones selected by 

 themselves, sometimes employ the ironwork of garden seats 

 (' Science Gossip ') . 



In this case, as in many others, we have also the conjoint 

 use of the natural and artificial instrument ; for the thrush 

 uses its beak to hold the shell which it dashes against the 

 hard iron. The dog seizes the trailing bridle of the runaway 

 horse or pony in or by its teeth, and so stops its flight. Dogs 

 or other animals that are taught to blow bellows must use 

 both their own mouths, teeth, paws, or hands, and man's 

 instrument. 



Whether, moreover, their instruments are natural or 

 artificial, or partly the one, partly the other, man's imple- 

 ments being worked by means of animal hands, paws, teeth, 

 mouths, or other natural organs, other animals, like man, 

 may be said to make the most of such instruments, to employ 

 them to the best effect. 



