3/2 "Journal of Comparative Neurology and Psychology. 



with each of the species observed, the neuter (worker) ants when 

 first put on the stage made random movements in every possible 

 direction. After a time in almost every case (over 95 per cent), 

 some one or more ants would find the way from the stage to the 

 nest and back. Such ants then began to convey pupae to the nest 

 regularly. Gradually they were joined by others. The time 

 required for ants to find the way home varied greatly; not only for 

 different species, and for different colonies of the same species, but 

 for the same colony at different times. That, however, is an 

 irrelevant matter. The essential thing is, not how long did it take 

 them, but which way did they go ? In the few exceptional cases 

 mentioned above, after a number of random movements, the ants 

 ceased to search for an outlet and settled down quietly upon the 

 stage. In such cases they usually collected the pupae in the center 

 of the stage and huddled over them. This getting lost was not 

 confined to any particular species and it was only an occasional 

 thing; no species got lost each time it was used. 



It is thought that the above experiments prove conclusively 

 that heliotropism does not influence the home-going of neuter ants. 

 This is in harmony with Loeb's conclusions, for he says ('02, p. 

 196), "I have never found true heliotropism in the workers." 



When winged females were placed on the stage with the pupae, 

 they would pass sometimes to the under side of the stage, some- 

 times they would roam about until they found the way home, and 

 in some cases they actually assisted in carrying the pupae home. 



In a very few cases (less than i per cent) males placed on the 

 stage with the pupae flew away; but in almost every case they 

 rushed to the under (shaded) side of the stage. Sometimes these 

 males again returned to the top of the stage; but in no case 

 observed by me, did any of these males reach the nest again until 

 carried there by the workers. 



Geotropism. — Any animal moving under the influence of geo- 

 tropism is automatically forced to orient its body so that its axis 

 of symmetry is at right angles to the horizon; or, if that be impos- 

 sible, with that axis parallel with the component of gravitation 

 which lies in the plane along which the animal is moving. 



In the majority of experiments on heliotropism, the apparatus 

 was so arranged that the ants were forced to go down hill to reach 

 the nest. To determine whether geotropism led them downward, 

 the apparatus was so adjusted that the ants had to go up-hill to 

 reach the nest. The neuter ants readily learned the way home. 



