130 ANTS AND ANT LIFE. 



wall, ran along the ceiling to the string, which led them to. 

 the treacle-pot. They repeated this manoeuvre, relieving 

 each other in troops, until all the treacle had disappeared. 



Such a proceeding, one among hundreds of similar obser- 

 vations, necessarily suggests two questions, the investigation 

 of which cannot be avoided in a psychological view of 

 animals : 



First ; How do the ants find their way to a place very 

 distant from then* nest at which a source of nourishment has 

 been discovered, and which they are unable to see ? 



Second; By what means do they communicate to each 

 other the discovery of such a treasure and induce their com- 

 rades to follow them to such a place ? 



As to the first question, there can be no doubt that its 

 answer lies in the excessively fine scent of the ants, while 

 their sight appears to be rather weak. The first is so sensi- 

 tive, that the approach of a human hand to an ant road is 

 enough to startle the prudent little creatures. Lespes says 

 that if a hand is laid for a moment on an ant path while it is 

 clear and then taken away again, the first ant that comes 

 along starts back terrified as soon as it comes to the spot 

 touched, and generally runs away as fast as possible. A 

 second comes, and a third, and all act in the same way. At 

 last one appears which either has a less keen scent or is less 

 timid, and which passes the barrier. As soon as this has 

 been done without danger, all the rest follow. Forel made 

 just the same observation with Lasius emarginatus. If a 

 finger is put for a moment on its road when none is there, 

 the first ant that comes up stops suddenly, stretches its 

 feelers in the air and turns back. Soon others come up in 

 a clearly uneasy way, run up, search over the place, and do 

 not pass by the spot until they are convinced that there is no 

 danger. Forel says further that nothing is more necessary 

 in scientific ant observations than to keep the mouth and 

 nose covered with the hand, for that the lightest human 

 breath is sufficient to frighten the ants and to cause the 

 failure of the experiment. He kept an ant-colony (Strongy- 

 lognathus testaceus) with a jar of honey in a cage, or 

 vivarium, surrounded by a high and thick plaster wall. He 

 then ceased feeding another ant-colony (Camponotus hercu- 

 laneus) in the same room, so as to induce them to go out. 

 The Camponotus ran about everywhere, and by the help of 





