July 1, 1868.] 



HARDWICKE'S SCIENCE-GOSSIP. 



149 



mounted in balsam (fig. 141) ; of course neither fluid 

 nor bubbles could be seen ; the central rib might 

 indeed be interpreted as being hollow, but what 

 the nature of a fluid in such a position as inside 



Fig. HO. Lancet of sting of Humble Bee x 25. 

 a, Projection of lancet. 



the tubular rib might be, or what purpose it might 

 serve, it would be difficult to conjecture, for it is 



Fig. 141. a, Lancet of Wasp sting x 120. 

 b, End of sting, with lancets enclosed, x 80. 



admitted that the poison issues from the bag to the 

 sheath, and passes down iu a groove between the 



two lancets. That the central rib is hollow I think 

 there can be no doubt ; that there may be an 

 aperture at the tip of the lancet is quite possible, 

 but difficult of proof; and that the internal fluid 

 may be the poison is a legitimate hypothesis, until 

 it can be proved that the poison from the bag could 

 not find its way into the hollow centres of the 

 lancets. 



The difficulty in the dissection is this, that it is 

 almost impossible to trace the course of the neck of 

 the poison bag, in its passage among masses of mus- 

 cular fibres, to its end and exact point of attachment. 

 This difficulty has, I believe, been met by some simply 

 by cutting the knot they could not loose, and by 

 giving illustrations of hypothetically apparent 

 attachments where none could possibly be traced 

 or seen. 



At first sight, and upon superficial inspection, 

 it would appear that the arrangements of the levers 

 and muscular bands connected with the lancets 

 of bees and wasps present considerable variety and 

 many points of difference ; but upon the close 

 examination of many specimens it will be found 

 that the plan of structure, although sometimes 

 difficult to trace, is nevertheless similar in all cases. 

 The nature of the mechanism is best displayed in. 

 the sting of a wasp that has been well prepared, 

 mounted in balsam, and so placed as to give a side 

 view of the structure. Those who possess numerous 

 preparations of ovipositors from ichneumon flies 

 will find among them the most beautiful examples 

 of a similar mechanism. 



The poison bag of the Humble Bee (fig. 139) 

 is very large, and pear-shaped; its remote end 

 passes into a very long gland that, after many 

 convolutions, closes in a blind end. 



It is not easy to separate the gland from the 

 tracheae, &c, with which it is entwined, nor to 

 trace its course in its many convolutions. 



Viewed with transmitted light, the trachea;, being 

 filled with air, appears quite dark in colour, whilst 

 the gland itself is semi-transparent. This difference 

 enables the microscopist to distinguish both with 

 ease ; but to separate the gland from the tracheae, 

 and to determine whether it is single or bifurcate, 

 and has two ends, requires careful manipulation. 

 In the dissection from which I have drawn the figure 

 the gland appears to be single ; but then, although 

 I used every caution, I cannot say that some portion 

 may not have been torn away among the separated 

 tracheae. 



The poison bag of the Hive Bee is similar, but 

 the gland not so long as that of the Humble Bee. 

 The Carder Bee, one of, the wild bees, has also 

 the poison bag; but the gland in this case, as in 

 some others, at a short distance from the bag bifur- 

 cates, and then there are two glands each, with the 

 usual blind end. 



