50 ANIMAL INTELLIGENCE 
subject has been advanced by studies on a lower plane 
and by the process of comparison? Anatomy and 
mammalian embryology would scarcely be worthy of 
the name of sciences to-day but for studies conducted 
on simpler forms. Do not psychologists sometimes 
forget, as anatomists long did, that the human is 
scarcely to be comprehended apart from the study of 
simpler creatures? Should we not look at psychology 
as the naturalist now does at zoology, and endeavour to 
discover the various grades in psychic processes, if such 
there be, and it is only, so far as I can see, by com- 
parative investigation that their existence or non- 
existence can be established. 
To do such work at its best requires a knowledge of 
both biology and psychology, and an intimate acquaint- 
ance with the ways of animals. Closet lucubrations 
cannot be expected of themselves to advance com- 
parative psychology very much. 
Might not human psychology be made more objective 
still, and is not the amount of wheat garnered much 
out of proportion to the quantity of sheaves brought to 
the thresher? Has individual psychology received the 
attention it deserves? Might not the inductive method 
be more fully applied to psychology? I have long been 
convinced that differences for races and for individuals 
have been insufficiently recognised in physiology, and 
at last there seems to be a reaction against the former 
reckless leaps from frog or rabbit to man. 
The physiologist cannot, however, afford to ignore 
the frog or the rabbit even when his goal is man; nor, 
f I may venture to express an opinion, can the psy- 
chologist do so either without some loss—possibly 
great loss—to his subject. 
I hope to see published, in the next few years, 
detailed studies on many individual human beings of 
both sexes, and also on individual animals. We must 
