270 THE CANADIAN ENTOMOLOGIST. 



" polarization of the scent " to explain the objective difference between 

 the going and the returning tracks, without (says Wasmann) telling us in 

 what manner it is subjectively perceived by the ants. This theory is 

 attacked by Dr. Wasmann on the ground of its inapplicability in some 

 instances and contradiction in others. He declares that the phenomena 

 may be explained in a much simpler way by assuming a different form of 

 the scent which marks paths leading in different directions. He further 

 ascribes sensory sensations and powers of impulse to these insects in order 

 to account for their voluntary actions. His account (pp. 31 and 32) of 

 Formica sanguinea taking a short cut from one nest to another, instead of 

 following the ordinary path, is very suggestive of a true sense of direction. 

 Some visual perception of changes in their paths is perhaps indicated by 

 the observations recorded a few pages farther on. 



Can ants see ? The treatment of this (p.iery is masterly, and it is 

 impossible to do the author justice in a short review. After showing that 

 those ants which, like Formica, have well-developed compound eyes, are 

 possessed of good visual powers, and the ability to use their visual images 

 in various emergencies, he compares, them with some other genera, such 

 as Solenopsis ( S. fugax ), where the eyes, being composed of but four or 

 five facets, are of much less sensitivity, though by no means insensible to 

 light. Now is brought in a very pretty side issue, which bears, however, 

 on the main question, namely, that those guests of the mimicry type 

 which live with ants having well-developed eyes, copy their hosts in a 

 different way from those which dwell among small-eyed forms. Among 

 the large-eyed ants the mimicry by the guest begins in a resemblance of 

 colour, followed by some likeness in build, this latter not extending to an 

 actual copy of the details, but resting largely upon deceptive light reflec- 

 tions. Among guests of small-eyed or blind forms the mimicry begins 

 with a resemblance in sculpture and vestiture, and this is succeeded by a 

 likeness in build, which amounts to an actual similitude between the parts 

 •involved to the corresponding organs of the host ; it culminates at last in 

 the similarity of antennal structure between guest and host. These points 

 are brought out in two lithographed plates. The conclusions to which 

 they lead are these : In guests of such ants as can see well, the mimicry 

 aims to deceive the sense of sight of the host; in guests of ants which are 

 blind or nearly so, the mimicry aims to deceive the antennal sense of 

 touch. 



