HARDWICKE'S SCIENCE-GOSSIP. 



33 



through the tube, the poison contained in the bag ; 

 and here the use of the chitinous ridges in the tube 

 leading from the bag becomes apparent, as it would 

 otherwise collapse and stop the flow. I cannot see 

 what purpose they would serve if the poison were 

 forced out. On the return of the piston the semi- 

 circular pieces fold together, and so not only allow 

 of the passage forward of the other, but also return 



portion running from b to b l , fig. 19 ; in this place they 

 prevent the escape of liquid behind the piston when 

 it is passing forward. 



The point of next importance is how are these 

 movements produced ? There are in the sting two 

 pairs of somewhat obscure tendons, but which must 

 not be overlooked. Their position is rather difficult 

 to explain, but a reference to fig. 21 will show the 



Fig. 25. 



without materially impeding the flow'of the liquid. 

 The poison passes down the tube formed by the two 

 pieces b m , see fig. 23, A. In this figure will be noticed 

 a kind of spur marked a ; this is the appearance 

 presented (in section) of a thin ridge which passes 

 along the entire length of these ^parts, and which 

 when presssd together prevent the poison escaping. 

 Mr. Hyatt not inaptly calls them^valves ; the con- 

 tinuation of them will be noticed along the curved 



Fig. 26. 



arrangement. The piece c" carries a sort of platform 

 from which the tendon a runs to the curved portion 

 which connects c with c\ and c x is connected with the 

 same piece by the tendon b. 



The first pair of muscles which probably come into 

 play are a pair found on the under side of the sting, 

 starting at the outer anterior angle of a, near the 

 point at which it hinges with b, and running to the 

 last segment of the bee's body in such a way that its 

 contraction will draw forward the whole apparatus. 

 This muscle is shown in fig. 25, where the others have 

 been omitted to prevent confusion. The position only 

 of the muscles is indicated in the diagrams, not their 

 size or shape. The folds in the tube connecting the 

 poison bag allow of its stretching to accommodate 

 itself to the altered position of the apparatus without 

 inconvenience. The next pair run from the anterior 

 ends of d in the direction of the length of the string, 

 and attached to the ridge in the centre of c ; see 

 2, fig. 26. The action of this pair is to depress the 

 whole of c 1 and <r lT , and to pull against the tendon 

 b, fig. 21. Another pair of muscles run from the 

 posterior portion of d, and are inserted into c at a 

 position at right angles to the first pair (3) ; they act 

 by bringing the two sides of the sting together, and 

 are opposed by the tendons a, fig. 21. The next pair, 

 or rather double pair, 4 and 4', connect a with c by 

 two muscles slightly diverging from one another. 

 These pull the plate a round its pivot at the anterior 



