78 APPENDIX. 



on a slip of glass ; but for all objects of large size, the 

 trough, or some similar contrivance, will be necessary. 



All insects that have been killed a long time, and whose 

 bodies are hard and brittle, may be softened by immersing 

 them in the solution already mentioned. 



The sting of the bee, wasp, hornet, and the ovipositors of 

 many flies, especially the ichneumons, are very similar in 

 their structure, and are generally found at the termination 

 of the abdomen, from which they may be obtained by first 

 slitting open the body of the insect with the fine scissors, 

 and afterwards removing the sting by using the scalpel and 

 needles. One or two of the latter should have their points 

 curved, which may easily be accomplished by heating the 

 ends red-hot in the flame of a candle, and bending them 

 with a pair of small pincers. At first sight the sting pre- 

 sents nothing to the eye but a horny sheath, tapering to a 

 point, with a slit broadest at its base and running down the 

 entire length ; within this sheath, on each side, lies a barbed 

 sharp-pointed spear in large insects, capable of inflicting a 

 severe wound, while the tube in which they are lodged 

 acts as a steadying rod, and as a channel to conduct a 

 virulent poison to the wound. The bag containing the 

 poison is placed at the root of the sting, and is connected 

 by a narrow neck with the sheath. The difficulty in the 

 dissection of the sting lies in getting the barbed points out 

 of the sheath and placing them on each side of it. The 

 following is the method employed by the writer. The sting 

 is placed in potash until it loses some of its rigidity ; it is 

 then transferred to a slip of glass or earthenware trough. 

 The curved needle-points are essential here. With one hold 

 the object firmly on the stage of the Microscope, insert the 

 point of the other into the opening at the base of the sheath 

 where it is largest, and gradually draw the point down the 

 tube ; this will make the opening wider and dislodge the 

 barbs ; arrange them on each side of the sheath, place the 

 sting between two glass slips subject to pressure. When 

 dry, soak it for a few days in turpentine, and mount in 

 balsam in the usual manner. A good specimen ought 

 to show the barbs very distinctly on each side of the 

 sheath. 



It will be found useful to the student to prepare three 

 specimens of this organ : 



1st. The whole abdomen showing the position the sting 

 occupies within it. 



2nd. The sting with the barbs lying within the sheath. 



