98 The Animal MM 



and others follow. The piece of paper is thus gradually 

 adopted into the ant road ; if it is subsequently removed, 

 the ants stop and are bewildered at the place where it was, 

 showing that the earlier traces of their footsteps, under 

 the paper, have evaporated. Again, Bethe thinks he has 

 evidence that the chemical stimulus left by the feet of 

 ants going from the nest is different from that deposited 

 by those going to the nest, and that ants on the way home 

 will not follow a track made by the feet of other ants on 

 the outward journey, and vice versa (51). Bethe found 

 that when the usual road to an ant nest had been inter- 

 rupted by the removal of a heap of sand, and the road 

 across the breach had been established solely by incoming 

 ants, the outgoing ants refused to follow it, and made a 

 new road for themselves (51). Wasmann thinks this may 

 have been done merely on account of the faintness of the 

 recently established path as compared with the old one 

 (762). Bethe observed also that if a strip of paper had 

 been adopted into an ant road, and was then, while an ant 

 was on it, rotated through 180 degrees, the ant stopped 

 and was disturbed on coming to the end of it (51). Experi- 

 ments on rotating ants were made also by Lubbock (441), 

 and seem to give puzzling and conflicting results ; it is not 

 clear why, even on the assumption that~ there is a difference 

 in odor between the road to the nest and that from the 

 nest, an ant on a road which led both ways should have 

 found her course interrupted by rotation. One fact, Bethe 

 thinks, shows that even assuming two road smells is not 

 enough. Ants of certain families (Lasius) which habitually 

 make regular and frequented roads can, if they come upon 

 one of these roads in wandering, at once take the proper 

 direction, either to or from the nest. Evidently the mere 

 presence of two smells would not enable them to do this. 



