56 INSECT MISCELLANIES. 



putorius, LINN.), which discharges a foetid vapour 

 upon its pursuers *. 



Many of the ants (Formica fcetens, F. fuliginosa, 

 fyc.) exhale a powerful and unpleasant smell, which 

 may, perhaps, be given them as a means of defence; 

 though it also appears to furnish them with the 

 means of following the routes of their companions to 

 and from their encampments. We once observed, on 

 Hampstead Heath, a track of the negro ant (F. 

 fused) several yards in length, leading to a numerous 

 colony, arid crowded through its whole extent with 

 foragers. By simply drawing a walking stick across 

 this track in several places, so as to obliterate the 

 scent, the whole train of foragers were instantly 

 thrown into confusion, and wandered about as if 

 blindfolded or tipsy; and though we remained upon 

 the spot for a considerable time to observe their 

 proceedings, they did not succeed in reuniting the 

 points of the track which we had dissevered, though 

 most of them found their way to the nest by cir- 

 cuitous and zig-zag routes t- The track in ques- 

 tion was not visibly hollowed out, as Huber says is 

 done by the wood-ant (F. rufa), to the extent some- 

 times of a hundred feet in length, and several inches 

 in breadth, or of the emmet (F. fuliginosa) which is 

 said to cut the grass in its pathways ; but marked 

 solely by the effluvia of the insects. The odour of 

 the wood-ant is so powerful, that a frog thrown into 

 one of their encampments will be suffocated in five 

 minutes J. 



The preceding statements show that ants are 

 endowed with an acute sense of smell, which is more 

 remarkably proved, as it appears to us, from some 

 other facts which have been otherwise explained. 

 Professor Bradley tells us that a nest of ants iu a 



* Kalm's Travels. t J. B. 



t Nouv, Diet, d'Hist. Naturelle, xii. 24. 



