256 ANIMAL INTELLIGENCE 
Later, the voice is used under such circumstances 
very persistently. 
At first the young pigeon can scarcely sit up in any 
fashion, but in a few hours this is possible, the greatest 
difficulty being the management of the head and neck, 
which often fall to one side or forward. 
The gradual progress in motor power and co-ordination 
has been fully noted in the diaries. 
By-and-by the young pigeon recognises its own nest 
when near it, and when alarmed will retreat to it. This 
is a matter of vision largely, though, as noted in the 
case of the young rabbits, there may be some sort of 
memory of distance and direction through tactile and 
muscular sensibility or otherwise. The subject is 
obscure and worthy of more study. 
So close is the relation between psychic and physical 
development, that, from the appearance of a bird, one 
who has observed closely could be able to predict its 
behaviour; and this seems to me to be undoubted 
evidence of some sort of correlation between the physical 
and the psychic. Now and then it will happen that 
from one pigeon having been hatched a few hours in 
advance of the other, by its being better able to persist- 
ently thrust forward its beak for food to the parents, it 
fairly starves the other one, or, if not completely, to 
such an extent that the difference in both physical and 
psychic development is very striking. Again, owing to 
innate vigour, one of the two birds in the nest may 
make a sudden advance, as was noted in the dog, in 
which case the same result as just referred to follows. 
There are many signs of development that appear 
progressively, such as changes in the shape of the skull 
and beak, the method of holding the head, the relative 
proportion of parts, etc.; but, upon the whole, the rate 
of feathering is a fairly good guide to progress, both 
physical and psychic. 
