THE EOOT-PEIXCIPLES OF MIND. 57 



remarked by Mr. Spencer that there is here a general corre- 

 spondence to be observed between the possession of organs 

 capable of varied actions, and the degree of intelligence to 

 which the animal attains. Thus of Birds the Parrots are the 

 most intelligent, and they, more than any other members of 

 their class, are able to use their feet, beaks, and tongues in the 

 examination of objects. Similarly, the wonderful intelligence 

 of the Elepliant may be safely considered as correlated with 

 the no less wonderful instrument of co-ordinated movement 

 which he possesses in his trunk ; while the superior intelli- 

 gence of the Monkey, and the supreme intelligence of Man 

 may no less safely be considered as correhited with the still 

 more wonderful instrument of co-ordinated movement which 

 has attained to almost ideal perfection in the human hand. 

 Again, and more generally, we may say that throughout the 

 animal kingdom the powers of sight and of hearing stand in 

 direct ratio to the powers of locomotion ; and the latter are 

 conducive to the growth of intelligence.* 



We may now observe that this correlation between 

 muscular and mental evolution — or, more generally, between 

 power of discrimination and variety of adaptive movements 

 — is only what we should expect to find a priori For it is , 

 clear that the development of the one function could be of no 

 use without that of the other. On the one hand, it would be 

 of no use to an organism that it should be able to discern a 

 stimulus as hurtful or beneficial, if at the same time it lacked 

 the power of co-ordinated movement necessary to adapting 

 itself to the result of its discernment ; and, on the other 

 hand, it would be equally useless that an organism should 

 possess the needful power of co-ordinated movement, if at 

 the same time it lacked the power of discernment which 

 alone could render the power of co-ordinated movement use- 

 ful. Now we know that all the mechanisms of muscular 

 co-ordination are correlated with mechanisms of nervous co- 

 ordination, and, indeed, that the former without the latter 

 would be utterly useless. Yet we know next to nothing of 



* The Dog and Cat seem at first sight to constitute an exception to the 

 principle above set forth ; but it must be remembered that both these 

 animals, and all their tribe, possess very efficient instruments of touch and 

 movements in their tongues, lips, and jaws, as well as to some extent in the 

 paws. I think the superior intelligence of the Octopus, among mollusks, is 

 to be attributed to the excepfional advantages which are rendered bj its large 

 and flexible, sensitive and powerful arms. 



