ANATOMY AND PHYSIOLOGY 



sex, as is notably the case in saturniid moths. In dragon flies, however, 

 this sense is relied upon far less than that of sight. 



Organs of Smell. By means of simple but conclusive experiments, 

 Hauser and others have shown that the antennae are frequently olfactory 

 though not to the exclusion of tactile or auditory functions, of course. 

 Hauser found that ants, wasps, various flies, moths, beetles and larvae, 

 which react violently toward the vapor of turpentine, acetic acid and 

 other pungent fluids, no longer respond to the same stimuli after their 

 antennae have been amputated or else covered with paraffine to exclude 



the air. His experiments were con- 

 ducted under conditions such that the 

 results could not be ascribed to the shock 

 of the operation or to effects upon the 

 gustatory or respiratory systems; except 

 for having lost the sense of smell, the 

 insects experimented upon behaved in 

 a normal manner. It should be said, 



FIG. 130. Under side of left maxilla 

 of wasp, Vespa vulgaris. p, palpus; 

 pr, protecting hairs; tc, taste cup; th, 

 tactile hair. After WILL. 



FIG. 131. Longitudinal section of gustatory 

 end-organ (tc, of Fig. 130). c, cuticula; fc.hypo- 

 dermis; sc, sensory cell; tc, taste cup. After 

 WILL. 



however, that Carabus, Melolontha and Silpha still reacted to some 

 extent toward strong vapors even after the extirpation of the antennae; 

 while in Hemiptera the loss of the antennae did not lessen the response 

 to the odors used. These facts indicate that the sense of smell is not 

 always confined to the antennae ; indeed the maxillary palpi are frequently 

 olfactory, as in Silpha and Hydaticus; also the cerci, as in the cock- 

 roach and other Orthoptera. Experiments indicate that an insect per- 

 ceives some odors by means of the antennae and others by the palpi 

 or other organs. Hauser found that the flies Sarcophaga and Calli- 

 phora, after the amputation of their antennae, became quite indifferent 

 toward decayed meat, to which they had previously swarmed with 



