94 The Animal Mind 



twenty years, was brought to him, and from it a female 

 hatched. Sixty males sought her within a few hours after 

 she reached maturity. Fabre noticed in this and other 

 cases that shutting the female in an air-tight box prevented 

 the males from being guided to her, but that the smallest 

 opening was enough to allow the odor to escape; that 

 the males were not in the least confused or led astray by 

 placing dishes of odorous substances about, and that they 

 would seek anything on which the female had rested for 

 a time, a fact which suggests that the stimulus is a secre- 

 tion of the body, as it is known to be in silkworm moths. 

 Fabre offers the suggestion that smell stimuli as they are 

 operative in the animal kingdom generally may be of two 

 classes : (i) substances which give off particles in vapor "^ 

 or gas, and (2) substances which give off a form of vibra- 

 tion. Our own olfactory sense is Hmited to the first class 

 of stimuli, but some animals, notably insects, may be 

 sensitive to both (216) . Certainly the marvellous sensitive- 

 ness involved in these mating reactions suggests a kind of 

 response to stimulation unknown in human experience. 



§ 24. How Ants Find Food 



In many ways the Hymenoptera are the most interesting 

 of insects, particularly those members of the order which 

 have developed community life. Their reactions to chemi- 

 cal stimulation have been the subject of a large mass of 

 literature, some of the more important results of which 

 we may now undertake to survey, considering ants, bees, 

 and wasps successively. Sir John Lubbock was among 

 the earliest observers to indicate the great importance of 

 chemical stimuli in the life of ants. In the first place, 

 he demonstrated that it is by chemical stimulation that 



