264 ANIMAL SKETCHES. CHAI>. 



unnatural to suppose that in insects the spiracles were 

 the seat of this sense. Modern research, however, tends 

 more and more clearly to localize the sense of smell, as 

 first suggested by Reaumur, in the feelers or antennae. If 

 the feelers of a cockroach be extirpated or coated with 

 paraffin, he no longer rushes to food, and takes little 

 notice of, and will sometimes even walk over, blotting- 

 paper saturated with turpentine or benzolene, which a 

 normal insect cannot approach without agitation. Carrion 

 flies whose antennae have been removed fail to discover 

 putrid flesh ; and E. Hasse has observed that male humble- 

 bees, whose antennae have been removed, cannot discover 

 the females. The sensory elements are cavities covered 

 over with a thin layer of chitin, which is marked with 

 oval thickenings. Within each cavity is a tapering nerve- 

 end cell. They are larger and further apart in the queen- 

 mother and the worker than in the drone, which is stated 

 to have nearly 20,000 such smell-hollows in each antenna ; 

 the male cockchafer having nearly twice as many ! 



The sense of smell is held by some observers to enable 

 ants and bees to recognize each other. Sir John Lub- 

 bock's experiments seem to establish the fact that the 

 recognition of ants is not personal and individual ; and 

 it occurred to Dr. McCook to test the olfactory hypo- 

 thesis by endeavouring to ascertain whether, in presence 

 of an overmastering scent, ants were unable to distinguish 

 friend from foe. Selecting for experiment some pavement- 

 ants who were engaged in a free fight, he introduced a 

 pellet of paper saturated with eau de Cologne. The effect 

 was instantaneous : the ants showed no sign of pain, dis- 

 pleasure, or intoxication, but in a very few seconds the 

 warriors had unclasped mandibles, relaxed their hold of 

 enemy's legs, antennae, and bodies, and, after a momentary 

 confusion, began to burrow galleries in the earth with the 



