No. 378.] REVIEWS OF RECENT LITERATURE. 44I 
Forel found that ants of different nests could be brought together 
without one seizing the other, provided the antennz be first removed. 
He held that the sense of smell was located in the antenna, and that 
it is through this sense that ants of the same nest are recognized. 
But unless it had been shown that each ant learns in its individual 
life to answer the smell of its own nest fellows in a friendly, and that 
of strange ants in an unfriendly, manner, and that it does not do this 
ab-ovo, it is not proved that we are dealing with “knowledge ” or 
“ thought.” 
An ant smeared with an extract of the bodies of its own nest 
fellows is received when placed on its own nest, but seized if smeared 
with an extract of strange ants. This was tried in several cases and 
held true in each. : 
An ant if first bathed in 30% alcohol, then with water, then 
smeared with the extract of another species, will be received by the 
colony from which the extract is made. From the fact that the 
strange ant may be many times larger than those among which it is 
introduced and of a different color, it is proved that form or color plays 
no rôle, but as the presence of a strange ant disturbs them when 
several millimeters away, it would appear that a volatile chemical 
material is concerned in the different reaction of ants toward their 
fellows or toward strangers. If the ant be washed with 30% alcohol 
and water, and as soon as dry returned to the colony, it will be 
seized, but if kept away twenty-four hours and then returned, the 
colony will receive it. From this and Lubbock’s experiments it is 
shown that this volatile material, which is called “ Neststoff,” is alike 
for individuals of the same nest, and every nest has its characteristic 
“nest material,” which is produced by each individual. 
Young ants, of a Lasius nigra nest, which had never met a stranger, 
were allowed to mature and harden in a box, then some were placed 
on a nest of Tetramoria, which were thrown into the greatest unquiet; 
some were placed on their own nest, where they ran quietly among 
their nest fellows. A few Tetramoria were placed in the box with 
the remaining ants, and the Tetramoria were at once attacked. 
Nothing here had been learned but that the different reactions toward 
like and unlike “nest materials” are inherited. Like material (that 
produced by ants of the same nest) constitutes no stimulus, but 
unlike “nest material” calls forth a reflex of either fighting or 
fleeing, depending on the amount present. 
Ants, if confined in a gauze box on their own nest, will not be 
noticed but allowed to starve. Ants of another nest placed in the 
