No. 378.] REVIEWS OF RECENT LITERATURE. 443 
until the path is well established across it and then removed, the 
space from which it was taken becomes as great a hindrance as the 
paper when first laid down. The drawing of the finger across a path 
leading over a glass plate will cause the same result as the paper strip. 
In the first case the guiding material is covered up, in the second 
it has passed off naturally, while in the last it has been wiped away. 
Loaded ants, even if picked up, rotated, and placed on the path 
backward, always go toward the nest. A path was led across a board, 
a section of which could be reversed, thus making a part of the path 
lead in the opposite direction from which laid down. When reversed, 
the next ant on coming to the section from either direction would 
stop, flourish its antennæ over the path, run first to one side and 
then the other, but would not proceed. If the section was not 
reversed until the ant was on it, the ant would continue on its way 
across the section, but on coming to the place where the section 
ended, instead of going on it would act as described above. These 
and other similar experiments leave little doubt that there is a polari- 
zation of the guiding material; but to say it is polarized does not 
explain all phenomena. Unless the ants walked home backward or 
deposited the material backward while coming home, there would be 
nothing present to indicate the direction of the nest. One experiment 
showed, however, that outgoing ants follow the paths of incoming 
ants with difficulty, and vice versa. This indicates the existence of 
two different guiding materials in the same path, one an incoming 
guiding material, the other deposited by outgoing ants. 
Lubbock thought that he had proved that ants communicate with 
one another, but Bethe uses one of Lubbock’s own experiments to 
show that it proves nothing. If a handful of pupz placed on a piece 
of paper near the nest be found by an ant, soon numbers of ants will 
be carrying the pupa home; but if an ant be carried to the pupz and 
when it has taken one, it be aided to find its way home and so on for 
several trips, using the same ant each time, no other ants ever find 
the pupæ. In the latter case no path is laid down zo the pup, hence 
there is nothing to guide the ants to them, while in the former experi- 
ment they had a path to guide them. All of Bethe’s experiments to 
ascertain the presence of any communication between ants could as 
well be explained through simple physiological stimuli as through 
intelligence. 
Several experiments, calculated to call out the intelligent action of 
ants, should they possess such even in the most meager degree, were 
carried on, but all with negative results. 
