ANATOMY AND PHYSIOLOGY 



101 



Longitudinal section of a portion of a 

 COCKrO3.Cn caudal appendage of a cricket, Gryllus 

 domesticus. b, bladder-like hair; c, cutic- 

 ula; h, hypodermis; n, nerve; ns, non- 

 sensory setae; sc, sense cell; sh, sensory 

 hair. After VOM RATH. 



insects ; thus there are as FlG - ! 34- 



many as 17,000 on each an- 

 tenna of a blow fly (Hicks). 



The male of Melolontha vul- 



garis, which seeks out the 



female by the sense of smell, 



has according to Hauser 39,- 



ooo pits on each antenna, and 



the female only 35,000. Pits 



presumably olfactory in func- 

 tion have been found by 



Packard on the maxillary and 



labial palpi of Perla and on 



the cerci of the 



Periplaneta americana. Vom 



Rath has described four kinds 



of sense hairs from the two 



larger of the four caudal appen- 

 dages of a cricket, Gryllus; some 

 of these (Fig. 134) may be olfac- 

 tory, though possibly tactile. The 

 same author found on the terminal 

 palpal segment in various Lepidop- 

 tera a large flask-shaped invagina- 

 tion (Fig. 135) into which pro- 

 ject numerous chitinous rods, each 

 a process of a sensory cell, which 

 is supplied by a branch of the prin- 

 cipal palpal nerve; these peculiar 

 organs are inferred to be olfactory. 

 The chief reason for regard- 

 ing these various end-organs as 

 olfactory is that they appear 

 from their structure to be better 

 adapted to receive that kind of 

 an impression than any other, so 



FIG. 135. 



Longitudinal section of apex of 

 palpus of Pieris. c, cuticula; h, 



sc, sense cells. After VOM RATH. 



