240 SUPPOSED RECOGNITION BY SCENT. 



concluded, he returned them to the nest, some after 

 eight, some after forty-one days. Those which were 

 returned after eight days were at once recognized, 

 while as regards those which had been forty-one days 

 away from home. " On reculait de part et d'autre, se 

 menapait des mandibules, s'examinait a fond avec les 

 antennes, se mordait meme. Plusieurs memo allerent 

 dans leur irritation jusqu' a essay er de decapiter et 

 meme a decapiter quelques-unes de leurs anciennes 

 compagnes et soeurs avec leurs mandibules (c'est le 

 mode de combat des Camponotus) ! Les fourmis vernies 

 prirent part a ces rixes aussi bien que les non vernies ; 

 je les vis meme attaquer, et elles etaient a peine 

 moins adroites. Les combats ne cesserent entierement 

 qu'au bout d'un ou deux jours, et, a part les quelques 

 victimes du premier jour, Tincident se tormina par une 

 alliance." 



Forel seems to entertain no doubt that the recog- 

 nition is effected by a form of smell, which he terms 

 ** odorat au contact." He says, " Beaucoup d'insectes 

 ont en outre une sorte d'odorat au contact que nous ne 

 possedons pas et qui permet entre autres aux fourmis 

 de distinguer leurs compagnes de leurs ennemies." 



His observations, however, do not favour the hy- 

 pothesis that the recognition may be by smell. If 

 the ants recognized their companions by any odour 

 characteristic of the community, the lapse of thirty 

 days could not have made any difference. Here the 

 question of memory would not enter, because the per- 

 ception of the odour would in both cases be continually 

 before them. M. Forel is so excellent an observer, 

 and has so great a knowledge of the ways of ants, 

 that his opinion is entitled to great weight. It 



