SO BRITISH ANTS. 



the obstacle is at once crossed, the procession of ants being in no 

 way interfered with I have observed the similar behaviour of a 

 single " homing " worker of F. rufibarbis (p. 323). 



If the eyes of a Donisthorpea be covered with varnish, it finds its 

 way as before, but if a Formica be treated in this manner, it is 

 unable to do so. These facts prove that smell is the predominant 

 feature in some cases, and sight in others. 



Memory also helps ants in finding their way workers of Polyergus 

 rufescens hunting for colonies of Formica fusca will locate various 

 nests, but it may be days or weeks before the slave-makers will 

 raid any particular one of them. No track of any kind could be 

 left, and memory alone must help them to go direct to this nest 

 (the same procedure is noted for Formica sanguinea, p. 290). Again, 

 when an ant finds a suitable place for a new nest at some distance 

 from the old one, returns home, and induces her companions to 

 move to this spot, the ant must remember where the selected spot 

 was ; nor can this be said to be a pure reflex action. 



Very many authors, including Bonnet, - Brun, Cornetz, Miss 

 Fielde, Forel, Huber, Lubbock, Santschi, Turner, Viehmeyer, 

 Wasmann and Wheeler, etc., have written at considerable length 

 on this subject, but it is only possible to touch very briefly on some 

 of their views. 



Wasmann has clearly demonstrated that Bethe's polarization 

 theory is inaccurate. 



Lubbock, Turner and Viehmeyer show that ants are partly in- 

 fluenced, in finding their way, by the rays of light. It is hardly 

 necessary to mention that ants can find their way in the dark, and 

 that some species are nocturnal in their habits. 



Cornetz 's theory is that ants are endowed with a special sense of 

 what he calls " pure direction," being guided by some mysterious 

 inner impulse. This compels them to move on continuously, up 

 or down, round and round, right or left, and keep on doing so what- 

 ever happens, while the impulse lasts. If it is transported elsewhere, 

 no matter, it still moves on as before. He thinks the human mind 

 can only conceive of direction as being aimed towards some particular 

 point of space, but the ant's conception of space may be something 

 quite different, and this may account for its behaviour being 

 sometimes unintelligible to us. Santschi has recently made a 

 number of new experiments ; his main points seem to be these : 



1. Cornetz's "pure direction," and all similar hypotheses of a 

 special sense are quite unnecessary. 



2. The phenomena which Cornetz sought to explain, can all be 

 explained by natural causes. Without actually seeing distant 

 objects, an ant's visual apparatus may convey to it impressions 

 received from them, which impressions may stimulate and influence 

 the creature's movements. 



3. Only one lens of a compound eye can transmit direct rays 



