[MILLS] PSYCHIC DEVELOPMENT OF YOUNG ANIMALS 211 
regards all these, the latent period is relatively very long. At birth, and 
up to the third day, though it is likely that all these powers exist in the 
animal, the evidence is feeble. 
Motor power is restricted to such an extent that the animal can 
crawl only and but slowly. 
Tactile sensibility, the sense of pain, and the temperature sense, 
reach their highest degree of development earlier than hearing and 
vision. 
Hearing is established before seeing, and reaches its greatest perfec- 
tion sooner than vision. 
In the progress of all the senses to full development, the course, 
while marked by definite steps, is often so rapid that distinct advances 
may sometimes be noted in a single day. 
Not only in the development of the senses, but in all other phases of 
progress has this been clearly evident in the case of the kitten under 
observation. 
Apart from the senses, etc., there seems to be a definite order in 
which all the features of feline nature appear, e. g., purring, crouching, 
stalking, etc. ‘ 
Certain physical changes are correlated in time with certain psychic 
developments, the significance of which is in some cases clear, in others 
obscure. 
