IN THE VERTEBRATA. 81 



butterflies (Wood), fish such as eels (Houzeau), cod, carp, 

 gold-fish serpents (Houzeau), and the toad (Wood). But 

 the same performance or proceeding the obeying of an order 

 or command of man obviously varies in its character and in 

 the nature and number of mental powers involved. In order 

 to analyse such an apparently simple performance, we must 

 consider, on the one hand, the variety of man's orders, and 

 on the other the various forms of, and motives for, obedience. 

 In the lower classes of cases man's order is simply a call to 

 be fed, and he may use a whistle or a bell, or peculiar voice- 

 sounds of his own. This is common in the case of various 

 tame fish, such as those of the Irrawaddy, described by Dr. 

 John Anderson, of the Yunnan expeditions. In the higher 

 class of cases man gives verbal orders, or a mere look or 

 gesture suffices, and his dog undertakes complex and difficult 

 commissions, which it executes with amazing promptitude 

 and sagacity. In the lower class of cases there is usually an 

 expectation to be fed, which is associated sometimes with a 

 partiality for being caressed ; while in the higher class of 

 cases there is not unfrequently a sense of duty, a pleasure 

 in giving gratification to man by the carrying out of his 

 behests, without any immediate, or perhaps even ulterior, 

 hope of reward, except that of a moral kind the expression 

 of human approbation. 



