THE PSYCHIC DEVELOPMENT OF YOUNG ANIMALS 213 
to enlarge the opening—in fact, he behaves in this very 
much like a mature dog. 
56th day.—When he is out of his compartment (the 
door open) and he is told to go in, and one stamps with 
the foot, he retreats to his box, but soon wants to come 
out again. 
63rd day—He now mingles with all the dogs of the 
kennel, large and small, seems to enjoy the life, and 
manages to adapt admirably to his entire environment. 
69th day.—Prior to defeecation moves about, smells, 
turns round and round, etc., just like an old dog. 
Shows sexual feeling, if one may judge by his actions 
towards a mature bitch. 
87th day.—Since the last record, his progress in 
adaptation and in general development has been steady. 
As the chief stages in development had been now over- 
taken, he was removed to my laboratory for experiment 
on the brain. 
Remarks on the Diary. 
Observations on the temperature sense, tactile sensi- 
bility, and the sense of pain were not made as early as 
desirable in the pure-bred puppies, but this omission 
was made good in the present case, as the diary shows, 
and there can be no doubt that these senses all exist 
from the moment of birth. The evidence that true 
smell, as distinguished from the mere sense of irritation 
of the nose by pungent vapours, is less conclusive, 
while that for taste is more doubtful still. 
The increasing development of tactile sensibility, and 
especially the readiness of the nervous system to respond 
to stimuli acting on the nasal mucous membrane, is well 
illustrated by the observations recorded at different 
times in the early life period of the puppies. 
Both smell and taste are very feebly developed before 
the eyes are open, but about the 10th day there was 
