THE DRIl'EK .L\D LEGIOXARY AXTS. 265 



In captivity Ecitons are remarkably restless, at least at certain 

 times during the day. Part of a fine colony of E. scliinitii which I 

 kept some years ago, exhibited this restlessness in a striking and ludi- 

 crous manner. The colony was at first confined in a tall glass jar on 

 a square board surrounded by a water moat. The ants kept going up 

 and down the inside of the jar in files for many hours. Finally I 

 removed the lid. The file at once advanced over the rim and descended 

 on the outer surface till it reached the circular base of the jar where 

 it turned to the left at a right angle and proceeded completely around 

 the base till it met the column at the turning point. To my surprise 

 it kept right on over the same circumference which was long enough 

 to accommodate all the individuals. They continued going round and 

 round the circular base of the jar, following one another like so many 

 sheep, without the slightest inkling that they were perpetually travers- 

 ing the same path. They behaved exactly as they do on one of their 

 predatory expeditions. They kept up this gyration for forty-six 

 hours before the column broke and spread over the board to the 

 water's edge and clustered in the manner so characteristic of this and 

 the allied species (E. opacithora.r, smnichrasti, etc.). I have never 

 seen a more astonishing exhibition of the limitations of instinct. For 

 nearly two whole days these blind creatures, so dependent on the 

 contact-odor sense of their antennae, kept palpating their uniformly 

 smooth, odoriferous trail and the advancing bodies of the ants imme- 

 diately preceding them, without perceiving that they were making no 

 progress but only wasting their energies, till the spell was finally 

 broken by some more venturesome members of the colony. 1 



In conclusion attention may be called to certain problems that are 

 suggested by our present meager knowledge of the Dorylinse. Besides 

 the investigation of the species with a view to obtaining all the phases 

 and thus clearing up the taxonomy, we are in great need of a fuller 

 insight into the domestic economy of these singular insects. As yet 

 no one has been able to observe the methods of rearing the brood and 

 the mating of the sexual forms, which must, of course, take place 

 without a true marriage flight. Nor has it been possible to plot the 



1 1 have found a remarkable observation of the same kind recorded by Fabre 

 in the sixth volume of his incomparable " Souvenirs Entomologiques." He 

 describes an army of caterpillars of the " processionaire du pin" (Cnethocampa 

 pityocampa) going round and round the outside of a large vase 1.35 m. in 

 circumference for seven days ! During this period the caterpillars were on the 

 march 84 hours altogether, stopping to rest on their path only when overtaken 

 by the cold of the night, and not actually deviating till the eighth day. Fabre 

 estimates that the caterpillars crawled around the vase 335 times. In this case 

 the insects were not guided by contact-odor like the Ecitons, but by the silken 

 thread spun by each individual over the surface traversed. 



