[mills] the psychic DEVELOPMENT OF YOUNG ANIMALS 23 



The ease with which reflex actions are excited on the very first day 

 of existence in the rabbit is striking and remains a very distinct peculi- 

 arity ; and on the same day the paws were used to wipe away an offend- 

 ing substance placed in the mouth. On the third day scratching of a 

 surface was observed, an act which has no small part in the burrowing 

 life of rabbits. By the fifteenth day they eat, and from this date onwards 

 they progress rapidly to perfection of reflex and voluntary action. The 

 early and rapid development of chewing or eating movements soon associ 

 ated with the use of the paws to hold food contrasts in the most decided 

 way with the slowness of the development of good eating movements in 

 the dog and still more so in the cat. The rabbit's cortex is inexcitable 

 till about the period of the opening of the eyes on the ninth to the 

 twelfth day, and the movements in which the head and face parts 

 are concerned can be induced by electrical stimulation about this 

 time. It is to be specially noted that these movements can be produced 

 in the rabbit experimentally almost as soon as those of the fore-limb, in 

 fact, I question whether in some cases at least they are not excitable 

 earlier and with greater facility, i. e., with a weaker current. With the 

 hind-legs the case is altogether diflerent ; in fact, my investigations would 

 lead me to infer that the hind-legs are never related to the cortex in the 

 same way as the fore-limbs. In no case have I been able to establish to 

 my satisfaction the existence of a cortical centre for the hind-legs of the 

 same nature (to put the matter cautiously) as those for the fore-limbs, 

 head, face, etc. The relation between the early and all but simultaneous 

 development of the cortical centre for the fore-limbs and head (and 

 face) parts and the physiological and psychic manifestations of the young 

 rabbit afford one of the most beautiful and striking illustrations of 

 correlation known to me. 



IV. — The Cavy or Guinea-Pig. 



The cavy comes into the world able to take care of itself. It can in 

 a few hours, if not at once, run about quite well, eat, etc. It is at the 

 outset as far on in the path of development as a rabbit some days after 

 its eyes open, though in the end there is httle difference between these 

 two rodents physically or otherwise. 



Corresponding with this advanced physiological and psychic develop- 

 ment, the cortex is, as I have shown, excitable at or soon after birth, so 

 that here again there is rendered evident by experiment a close con-ela- 

 tion of the kind considered throughout this paper. 



V. — Birds. 



One learns how large a proportion of the possibilities, physiological 

 if not psychic, in the pigeon are not dependent on the cerebral cortex, or 

 even the entire cerebrum, by ablation of the latter. Movements, thouo-h 



