22 ROYAL SOCIETY OF CANADA 



of voluntary movements and the speedier perfection attained by each, 

 together with the more ready and complete utilization of experience, the 

 early intelligence, the strength of the will and the power of attention. 



All this is correlated with that earlier develo])ment of the cerebral 

 cortex which I have shown occurs in the cat, and there is probabl}^ a 

 greater difference than can be made manifest by our crude methods of 

 experiment. 



A very marked feature in the psychic development of the cat is 

 the early appearance of the play instinct^ and the perfection of the 

 fore-limb in carrying out the movements necessary for its manifesta- 

 tions. The cat has incomparably better use of the fore-limb at an 

 early date. I have recorded observations on play (with use of the 

 paws), as early as the twenty-second day, and, as is well known, the 

 kitten and the older cat have a variety and perfection of movement of 

 the fore-limbs never acquired by the dog. This is distinctly correlated 

 with brain development, for, as I have pointed out, movements of the 

 fore-limb are in the cat the first that can be induced by electrical excitation 

 of the cortex, and to this observation ray experience leads me to believe 

 there are practically no exceptions, while the case is very different for the 

 dog. Some investigators have expressed the opinion that the fore-limb is 

 also the first to respond in the dog, but this does not accord entirely with 

 my experience. It has occasionally been so in the puppies on which I 

 experimented, but in the large majority the hind-leg responded first. 

 Mongrels and pure-bred animals of different vai'ieties were used. I do not, 

 therefore, believe that the statement that the fore-leg in the dog is always 

 the first to respond to electrical excitation can any longer be maintained 

 as a sound generalization ; but it ma}^ be as I have suggested in my paper 

 on the brain that the truth is that sometimes the one and sometimes the 

 other limb is the first to react, and that large allowance must be made 

 in any treneral statement for individual and breed differences. 



III. — The Eabbit. 



Such a creature as the rabbit contrasts in the most marked manner 

 with the dog and the cat. 



A rabbit to the last is much more a creature of instincts and reflexes 

 pure and simple with relatively but little intelligence, all of which is in 

 harmony with its simple modes of existence. Its food is in the wild state 

 usually abundant, and as its escape from enemies is accomplished by 

 swiftness in flight or by taking refuge in its burrow, there is little in its 

 environment to develop intelligence. With the carnivora it is quite 

 otherwise. They obtain their food by cunning, stealth, stratagem— it 

 may be concerted action, as in the case of wolves, hyaenas, wild dogs, etc. 



1 The whole .subject of play in animals is exhaustively treated by Dr. Karl Groos 

 in his " Die Spiele der Thiere." Gustav Fischer, Jena, 1896. 



