3 J 



HARDWICKE' S SCIENCE-GOSSIP. 



" piston," moves up and down in the hollow portion 

 of c'. Now it will be seen by comparing A (fig. 23) 

 with B, that the surface of the piece upon which the 

 T-ridge is, and on which the part b ii{ slides, is vertical 

 in B, while in A it is much inclined, and in the series 

 of sections given by Mr. Hyatt the transitions from 

 one inclination to the other can be traced. It follows, 



explain my theory of the manner in which the poison 

 is ejected. In the first place the poison bag appears 

 to me to be composed of two coats, in neither of 

 which have I been able to see any trace of muscle. 

 Mr. Hyatt, in his paper before referred to, says, 

 " A sac or reservoir is connected with the base of the 

 sheath and discharges into it [a poisonous fluid] by 



Fig. 19. 



Fig. 20. 



Fig. 24. 



therefore, that b', the piston, in being moved along 

 from the anterior end to the posterior, is thrown over 

 to the inside, and the semicircular piece a (fig. 6) 

 being hinged to b, any movement posteriorly through 

 a fluid would press them apart. Turning then to 

 fig. 22, it will be seen that the cavity c' is smaller at 

 the lower end than at the upper. 

 This is, perhaps, a convenient point for me to 



the rapid contractions of its muscular 

 coats Rapid automatic contrac- 

 tions of the muscular coats of the poison 

 gland continue to pump out its venomous 

 contents." He, in the second sentence, 

 refers to his observations on a sting 

 extracted from a living bee. But if, as 

 I believe, the pieces b' t fig. 20, are alter- 

 p; g . 22 , nately moving in the length of the cavity 

 c', it will follow that the semicircular pieces 

 a, fig. 24, will open as they are pressed forward, and 

 with the inclination to one side which is necessarily 

 given to them as they move from one end to the other 

 (as explained by fig. 23, A, B), they will fill the whole 

 width of Ihe posterior portion of c x fig. 22. As the 

 piston moves forward it will drive before it any 

 fluid that maybe in this "cylinder" c', and at the 

 same time create a vacuum which will draw into it, 



