June, 19 16.] WhEELER: SlaVE-RaiDS OF AMAZON AnT. 117 



single colony thus formed flourished and grew to considerable size 

 by July i8, 191 1, when he took it into his garden and observed the 

 behavior of the amazons when he opened the nest and permitted 

 them to make slave-raids on various colonies of Formica fusca var. 

 glebaria and F. rufibarbis. Similar experiments were performed during 

 the summer of 1912 and 1913. July 14, 1914, when he released the 

 colony for the last time in a courtyard of his villa, the ants estab- 

 lished themselves in the soil and soon afterwards moved to another 

 more permanent nest. The amazons made several sorties till Oc- 

 tober 2, but secured no booty, as there were no nests of the slave- 

 species in the courtyard. The observations were very suggestive in 

 connction with the interesting problem as to how the amazon armies 

 are guided to the nests they plunder. Like Forel and myself, Emery 

 believes that exploring workers, which leave the nest singly, ascer- 

 tain the position of the slave colonies in the environment and are 

 thus able to determine at least the initial direction to be taken by the 

 army when it leaves the nest. I shall not discuss this difificult ques- 

 tion here, but will merely call attention in conclusion to the times of 

 sortie of the army as recorded in Emery's paper. These are given 

 as follows : 



191 1. Aug. 22 — 4.30 P. 



1912. " 17 — 5.00 P. 

 " 21 — 4.20 P. 

 " 24—4.30 P. 

 " 28—5.40 P. M. 



1913- July 5—4-50 P. M. 

 " 30—5-15 P- M. 

 1914. " 16 — 6.00 P. M. 

 " 17—6.30 P. M. 

 " 25—7.00 P. M. 

 Aug. 8—5.30 P. M. and 6.15 P. M. 

 , Oct. 2—3.30 P. M. 

 It will be seen that all but one of the sorties were very late, be- 

 tween 4.20 and 7 P. M., the average time being about 5.30 P. M. This 

 is much later than the average time of sortie of Swiss colonies of 

 rufescens or of the Calif ornian breviccps, and indicates that the tem- 

 perature during July and x^ugust in northern Italy (presumably near 

 Bologna), in such enclosed spaces as gardens and courtyards, may be 



