332 N. E. McINDOO 



shaft. From the drawings (figs. 16 and 23) it is clear that the 

 structure of the pores on the sting is identical with that of the 

 pores on the legs and wings, and that the pores of the sting open 

 internally into the body cavity {BC) and not into the poison 

 canal of the sting (PsnCl). 



In regard to the pores of the sting Snodgrass ('10) says: 



The reader .... will see often repeated the statement that 

 the poison leaves the sting both by a ventral opening between the lan- 

 cets near their tips and by several lateral pores near the ends of the 

 lancets opening from the poison canal upon the bases of the barbs. The 

 writer, however, has never been able to observe the exit of the poison 

 from any such lateral pores, while, on the other hand, it is very easy to 

 watch it exude from between the lancets on the ventral side of the 

 sting near the tip 



An examination of the end of each lancet does reveal a number of 

 oblique pores which have been figured by other writers, and they cer- 

 tainly open on the bases of the barbs as described, but their inner ends 

 apparenty communicate with the body cavity (be) of the lancet instead 

 of passing clear through the lancet and opening into the poison canal. 

 Furthermore, a paired series of exactly similar pores extends the entire 

 length of the shaft of the sheath, opening on its dorsal surface from the 

 body cavity. No one could possibly claim that the poison emerges 

 also through these pores, which, very curiously, do not appear to have 

 been described before, although they are even more conspicuous as 

 well as more numerous than those of the lancets. The writer has not 

 been successful in preparing histological sections of the sting which 

 show these pores, but they probably constitute the ducts of some kind 

 of subcuticular glands. 



From the foregoing quotation it is clear that Snodgrass con- 

 siders these pores as communicating with the body cavity of the 

 shaft and lancet and not of the poison canal. But instead of 

 being some kind of a subcuticular gland, they are connected 

 with sense cells and are thus sense organs. 



Summary 



To sum up, then, the olfactory pores consist of inverted flasks 

 in the chitin and spindlelike sense cells lying beneath the mouths 

 of the flasks. The bottom of the flask forms an external cov- 

 ering and about two-thirds of the space at the bottom of the 

 flask is occupied by a hollow chitinous cone which is not sepa- 

 rated from the surrounding chitin, but only stains less deeply. 



