Turner, Hoiiiiug of Ants. 377 



vum pass back and forth across a trench of water in order to con- 

 vey their pupae into their nest. They traveled back and forth 

 across the water for thirty hours until all of the pupae had been 

 removed. She performed two such experiments with the same 

 colony. To see if the ants left a scented trail on the water, she 

 experimented as follows : ( i ) She removed a few drops of water 

 from in front of an ant which was returnmg to the island. Out 

 of thirty-one ants thus treated, twenty-one continued across and 

 ten turned back. (2) She passed a knife-blade through the 

 water and around an ant returning to the island. Out often ants 

 experimented on none turned back. (3) She covered the surface 

 of the water with dust, and after the ants had been passing for 

 some time, removed the dust. The ants were not in the least 

 affected. These results led her to conclude that in crossing the 

 water the ants were dependmg upon something more than mere 

 footprints. 



Frequently I have noticed individual ants of most of our com- 

 mon species cross the water ditch that surrounds the Lubbock 

 island. Occasionally I have had whole colonies escape in that 

 way, but it has always happened when I was absent. On one 

 occasion I had a colony of Forelius maccooki MacCook escape in 

 that way. In this colony there were at least twice as many eggs, 

 larvae and pupae as workers and w^inged females. Since no pupae, 

 larvae or eggs were left behind, and since all of the workers do not 

 usually take part in carrying pupae, some of these ants must have 

 crossed the water several times. 



Wasmann ('01 ) states that if the surface-sand be removed from 

 the vicinity of the nest of busy Formica sanguineas, the ants con- 

 tinue to pass back and forth without noticing the change. In the 

 same paper Wasmann relates that he noticed another set of ants, 

 laden with cocoons, travel eighteen meters from one nest to a 

 former nest. On this occasion the ants neither used their antennae 

 to smell the way nor followed in each other's tracks. Each ant 

 marched along independently as though it knew the way 



These observations of Fielde and Wasmann serve to empha- 

 size the statement made above, that the home-going of ants is not 

 controlled solely by the olfactory sense. 



PiERON ('04) from experiments- of a different kind came to the 



- PiERox's experiments bearing on this point may be epitomized as follows: (i) He passed his finger 

 across the path. The ants on each side halted and usually spread out along the line of disturbance, 



