[mills] the psychic development of young animals 21 



of a litter of puppies, as shown in my paper on the dog (these Trans- 

 actions, 1894), will impress both the physiologist and the i)sychologist 

 with the rapidly increasing comi)lexity of the lil'e of a young dog, a com- 

 plexity in which reflex and voluntary movements, instincts, intelligence, 

 emotions and will blend in varying but ever augmenting degrees of 

 intricacy, with all of which the rapidly developing cortex is correlated, 

 and, as I have endeavoui-ed to show in earlier papers, there is a large 

 amount of somatic correlation over and above that of the brain, which 

 is constant as to period of development, but with variations for indivi- 

 duals and breeds. 



The rapidity of psychic development of a terrier as compared with 

 a St. Bernard is very striking, even within the first six weeks of life, but 

 persists to maturitj' ; and this, I have found, is correlated with a 

 ■decidedly slower functional development of the cerebral cortex in the St. 

 Bernard ; the difference in the motor co-ordinations in the latter and the 

 terrier is so striking within the first six or eight weeks of life as to be 

 ludicrous. 



II. — The Cat. The Dog and the Cat Compared. 



ISTearly all that has been said of the reflexes of the dog applies, of 

 course, to the cat. There are, however, as would be expected, some that 

 are peculiar to the cat, as hissing, which manifests itself at a surprisingly 

 early date in the kitten, long before the eyes open. 



As ]:)ointed out in my paper on the cat, there is a general and more 

 speedy development in this animal as compared with the dog, and this 

 holds even for reflexes, /. e., they reach perfection more rapidly ; in fact, 

 speaking generally, the cat develops faster than even the smaller 

 varieties of dogs as terriers. 



13y the sixteenth day the kitten specially observed by me licked its 

 paw. This, under the circumstances, can scarcely be regarded as a pure 

 reflex ; certainly dogs do nothing comparable to this at so early a date- 

 It also scratched its head with the hind leg on the sixteenth day. 

 Whether this be regarded as voluntary or reflex, it indicates that the cat 

 is in advance of the dog. 



Nothing could better demonstrate the more rapid pyschic develop- 

 ment of the cat than the earlier date at which it steadily follows a 

 moving object with the eyes or fixes them for some time on a stationary 

 one. In fact, the kitten does this at a time when it is still doubtful if 

 the puppy sees objects as such distinctly. 



On the eighteenth day the kitten climbed up the side of its box and 

 tried to get out. Nothing comparable to this occurs in the puppy till a 

 good deal later. It may be said that the history of the cat during the first 

 six weeks of its life contrasts strongly with that of the dog as regards 

 the more rapid development of reflex movements, the earlier appearance 



