HYMENOPTERA 



CHAP. 



Vol. V. ; so that here it is only necessary to give a diagram to 

 explain the terms used in the descriptions of the families and 

 sub-families of Aculeata, and to discuss briefly their characteristic 

 structures. 



The Sting of the bee has been described in detail by Kraepelin, 

 Sollmann, Carlet l and others. It is an extremely perfect me- 

 chanical arrangement. The sting itself- -independent of the 

 sheaths and adjuncts consists of three elongate pieces, one of 

 them a gouge-like director, the other two pointed and barbed 

 needles ; the director is provided with a bead for each of the 

 needles to run on, these latter having a corresponding groove ; 

 the entrance to the groove is narrower than its subsequent 

 diameter, so that the needles play up and down on the director 



with facility, but cannot be 

 dragged away from it ; each 

 needle is provided with an 

 arm at the base to which 

 are attached the muscles for 

 its movement. This simple 

 manner of describing the 

 mechanical arrangement is, 

 however, incomplete, inas- 

 much as it includes no 

 account of the means by 

 which the poison is conveyed. 

 This is done by a very com- 

 plex set of modifications, of 

 all the parts ; firstly, the 

 director is enlarged at the 

 anterior part to form a 

 PIG. s. sting of bee. A, One of the needles chamber, through which the 

 separated ; , the .barbed poini ; ?>, piston; needles play ; the needles are 



c, aim. u, 1 rans verse section of the 



sting: tit?, the two needles; e, bead for eacn provided With a pro- 



B 



needle moves, plays in the 

 chamber of the director, and forces downwards any liquid that 

 may be therein ; the poison-glands open into the chamber, and 

 the projections on the needles, acting after the manner of a piston, 

 carry the poison before them. The needles are so arranged on 



1 Ann. Sci. Nat. (7) ix. 1890, p. 1. 



