^6 THE INDUSTRIES OF ANIMALS. 



old chief, and partly by the fear inspired by his 

 muscular arms and ferocious canine teeth. (Fig. 9.) 

 He gives himself a great deal of trouble for the 

 security of his subjects, and does not abuse the 

 authority which he possesses. Always at the head, 

 he leaps from branch to branch, and the band follows 

 him. From time to time he scales a tall tree, and 

 from its heights scrutinises the neighbourhood. If 

 he discovers nothing suspicious a particular gutteral 

 grunt gives information to his companions. If, on 

 the contrary, he perceives some danger he warns 

 them by another cry, and all draw in ready to follow 

 him in his retreat, which he directs in the same way 

 as he guided the forward march. 



Apes are not alone in relying on the experience of 

 one of their members. Many other animals act in 

 the same way : antelopes, gazelles, elephants, who 

 advance in troops always conducted by an old male 

 or female who knows all the forest paths, all the 

 places favourable to pasture, and all the regions 

 which must be avoided. 



Others, more democratic, instead of giving up the 

 care of their safety to one individual, which cannot be 

 done without abdicating some degree of individual 

 independence, dispose around the place which they 

 occupy a certain number of sentinels charged to 

 watch over the common safety. This custom exists 

 among prairie dogs, mufflons, crows, paroquets, 

 and a great many other animals. The sentinels of 

 the crows are not only always on the watch, but they 

 are extremely discriminating; they do not give a 

 warning at the wrong time. It is certain that these 

 birds can distinguish a man armed with a gun from 

 another who merely carries a stick, and they allow the 



