THE PSYCHIC DEVELOPMENT OF YOUNG ANIMALS 149 
subject of pain on the first day, even in the first hour. 
This has been made good in part by brief extracts 
from a diary kept of a litter of Bedlington terriers, 
previously introduced. Such experiments are necessary, 
as the discomfort one witnesses in young puppies might 
be due in certain cases to internal and not to skin 
sensations. 
TACTILE SENSIBILITY.—Very striking, indeed, are the 
effects on a puppy of any age up to two months (and 
noticeable even in mature dogs) of stroking, smoothing 
movements with the hand. In some very young 
animals, as birds, I find a similar effect, due to placing 
the hand on them or over them. In this case the 
effect is largely due to the heat of the hand; in young 
puppies the gentle tactile stimulus is the principal, but 
not the sole cause of the quieting effect. In this way 
a puppy may, when very young, soon be put to sleep, 
ae. the activity of the nervous centres is inhibited by 
tactile sensations, so that the frequent lickings of the 
dam not only cleanse but soothe the puppies. There 
is, after the eyes are opened, a very rapid increase in 
the acuteness of tactile sensibility, well shown in the 
readiness with which a slight touch on the lips will 
induce motor response, especially well seen in sucking 
movements, etc. 
TEMPERATURE SENSE.—Experiments in this subject 
were, unfortunately, not made in the early days. How- 
ever, I tested a kitten, five days old, with an iron 
warmed and also with ice, getting decisive results of 
a positive kind. I think that it is likely that the 
temperature sense is well marked from the first, though 
the squirming, cries, etc., of young animals are not of 
themselves conclusive as to this. 
THE MuscuLaR SENSE.—On this subject a few words 
will suffice. Considering how numerous and perfect 
are the co-ordinated muscular movements of compara- 
