440 THE AMERICAN NATURALIST. [VoL. XXXII. 
previous process of learning, in which the action is not purely reflex, 
but is eventually regulated through psychical processes”; “sexual 
intercourse is instinctive in man, but is a reflex in beetles. A silk- 
worm spins its cocoon reflexly, but a bird builds its nest instinctively. 
Instincts are neither wholly reflex nor wholly psychic.” 
Individual diversity extends farther than is generally supposed; 
even the odors given off by individuals are characteristic, since 
through them bloodhounds are able to follow one trail unerringly. 
The first one of the two main divisions of the paper is devoted to 
a research on ants, and the first question asked is: 
“ Do ants of one colony recognize each other?” 
From the fact that an ant, if placed on a nest (not its own) of either 
the same or a different species, will be seized and often killed, it has 
been concluded that they know each other personally and distinguish 
between strangers and their own number, although some nests 
contain thousands of individuals. 
Lubbock investigated this subject and found that: 
1. After a separation of almost two years, individuals of Fomzca 
fusca were received in a friendly manner when placed back on their 
own nest. 
2. Pup, separated from their nest but cared for by workers from 
it, were received in a friendly manner without exception if placed 
back when grown. : 
3. If pupa were cared for by workers of another nest, it was 
different. Out of forty-four placed on their own nest, seven were 
attacked and thirty-seven received. Of fifteen placed on the foster 
worker’s nest, all were attacked. : 
4. An egg-laying queen was taken from her nest, and her subse- 
quent brood when grown was not seized when placed on the nest. 
These results led Lubbock to believe that there is no personal 
recognition among ants of one nest; and from the fact that chloro- 
formed ants were received by their own fellows but seized by individ- 
uals of a strange nest, he concluded that reception or rejection did 
not depend upon any sign or word, but what was at the bottom of 
the matter he did not understand. 
Romanes thought their methods of distinguishing each other were 
not capable of being understood by us, but that it was, through some 
kind of psychical process, a species of memory. 
McCook, observing that after an ant had fallen into water it was 
attacked when coming home, concluded that through the bath the ant 
had lost its peculiar odor, hence was no longer recognized. 
