992 



INSECTA. 



A, lateral view of the sting of the Bee. (Westwood.) 

 a, the sheath ; 6, terminal segment of the abdo- 

 men ; c, the barbs or proper sting ; d, the chan- 

 neled surface of the sheath of the sting in which 

 the barbs are concealed. 



B, the poison-bag and vessels of the sting of the 

 Anthophora return ^Newport) ; a, sheath of the 

 sting ; b, the dilated extremity of the poison duct ; 

 c, d, the bag ; e, efferential vessel ; /, the secretory 

 organs; g, their vessels. 



C, terminal segment of the abdomen of a saw-fly, 

 Trichosoma (Lyonet) ; a, dorsal end of the ter- 

 minal segment ; b, sheath of ovipositor or terminal 

 ventral arch ; c, d, the inner plates or saws, analo- 

 gous to the barbs, c, of the sting of the bee. 



D, one of the double lancet-pointed saws of 

 Athalia centifolice. 



at the tip in the bees (c) but much broader in 

 the saw-flies (C, c, d) and transversely striated, 

 forming the saws with which these insects are 

 provided: moreover these two pieces are re- 

 ceived in the bees into a canal (A, </), but in 

 the saw-flies this gutter is broad, flattened, and 

 divided into two separated parts, forming the 

 backs of the two saws. In the Ichneumons 

 these various parts are so slender that at the 

 first sight they appear to consist but of a single 

 piece : on more minutely examining the in- 

 strument, however, it will be found that it 

 consists of a scabbard, composed of two pieces, 

 inclosing a fine hair-like bristle, which is, in 

 fact, the exact analogue of the stinging part of 

 the bee's sting, consisting of three pieces." 

 This organ constitutes both a means of defence 

 and also of depositing the eggs. There have been 

 some doubts with regard to this fact in the 

 bees, some having questioned whether the sting 

 is at all employed in oviposition by these in- 

 sects ; but a most careful and accurate ob- 

 server, Dr. Bevan, distinctly states that the 

 ova pass along the sting of the bee to be de- 

 posited, and this statement is confirmed by 

 the fact that this is certainly the case in the 



analogous instrument of the saw-flies, as we our- 

 selves have distinctly witnessed in Athalia 

 centifolite. The analogy, therefore, of the sting 

 with the ovipositor of the Gryllida, of the saw- 

 flies, and other insects, is distinctly proved. In 

 Athalia the ovipositor is a very interesting 

 organ. It occupies the under surface of the 

 seventh and eighth segment of the body, and 

 is approximated to the posterior margin of the 

 sixth, a part of the seventh having been re- 

 moved. Four tendons for the insertion of 

 muscles originate from the extremity of the 

 two halves of the ovipositor. In the mem- 

 brane that unites on the under surface the two 

 halves of the ovipositor, is situated the vaginal 

 orifice between the two saw-shaped organs 

 (C, c, d, D). Each of these parts is composed 

 of two plates applied together back to back, 

 and which together form a pointed instrument 

 resembling a lancet (D). The upper one of 

 these plates (i) is furnished with small sharp- 

 pointed teeth directed backwards, and the 

 under one (&) with fourteen long and slightly 

 convex ones. With the point of this instru- 

 ment the insect pierces the edges of the leaves 

 of the turnip, separating the cuticle with its 

 saw preparatory to depositing its egg, which is 

 conveyed along its inner surface, which is 

 slightly concave to allow of its safe transit 

 along the plates. Posteriorly and external to 

 these plates are the two sheaths of the ovipo- 

 sitor (C, b) analogous to one portion of the 

 ovipositor of the Gryllida. In all those Hy- 

 menoptera furnished with an ovipositor there is 

 also an apparatus for secreting a peculiar fluid, 

 and this apparatus is believed to be analogous 

 to the appendages of the male organs above 

 alluded to, the use of which is not well under- 

 stood. In the female these parts consist of an 

 excretory duct, and bag, or receptacle for the 

 fluid, a convoluted efferential vessel, and proper 

 secretory organs. In the wild bee, Anthophora 

 retusa (B), at the base of the sheath (a) in 

 which the two barbs of the sting (A, e} are 

 concealed, is a smooth dilated space, into which 

 the poison is first received at the base of the 

 sting. The poison is conveyed to this space 

 by the efferential duct (c) from an oval sac (d); 

 in which it is accumulated as secreted, and into 

 which it is poured by a very large and much 

 convoluted efferential vessel (e\ which receives 

 the fluid from two cceciform glandular organs 

 C/'J, which unite as they enter the efferential 

 vessel. These secretory organs receive at their 

 apparently closed extremity each a minute 

 vessel, which we have distinctly traced to some 

 distance from them, but not to its termination. 

 When the poison is ejected from the bag (d) 

 into the base of the sting, it passes along be- 

 tween the two barbs, as in a little gutter, into 

 the wound. Swammerdam delineated these 

 parts in the honey-bee, but did not notice the 

 vessels proceeding from the secretory organs. 

 In another insect of the same class there are 

 similar structures. Thus, in Athalia (JigA39\ 

 the bag (g) is oval, but the efferential vessel is 

 entirely absent, the fluid being poured directly 

 from the secretory vessels (A) into the bag with- 

 out passing along any other tube. The vessel is 



