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articulated respectively to the large sheath plate and to an- 

 other plate, the oval plate. Determine the attachment of the 

 muscles to the plates and find what movements of the lancet 

 the contraction of the different sets of muscles would cause. 

 Note that the lancets are elastic and bend easily. 



The large muscles attached to the sheath plates were at- 

 tached to the wall of the abdomen and function to give the 

 thrust that sets the sting. After the sting is drawn from the 

 body of the bee the muscles attached to the plates continue 

 active, and the sting works deeper and deeper in. Understand 

 why it works in instead of out. 



2. Lying near the base of the shaft is a large poison sac 

 or reservoir, which is very muscular. It receives its poison 

 from the poison gland, a long and narrow coiled tube that is 

 bifurcated near its free end. It discharges the poison by 

 means of the contraction of the muscles of its walls through a 

 rather large, short duct into the space inclosed by the sheath 

 and the two barbs. Each barb bears a prominence that 

 serves as an injector, which moves backward and forward 

 with the barb to which it is attached, in an enlargement of 

 the basal portion of the sheath. It may be seen in the prep- 

 aration. In this way poison is forced into the wound. Poison 

 may also be admitted to the cavities of the lancets, which 

 are hollow, and escape through minute pores near the barbs. 



3. Lying near the base of the shaft of the sting, some- 

 times covered by the poison sac, may nearly always be found 

 the last pair of abdominal ganglia, from which nerves may 

 be traced to the muscles that are attached to the plates. 



Understand the whole mechanism, how it is operated and 

 its use. 



4. Catch a living bee by the wings and press the end of 

 the abdomen against a piece of soft leather, such as a leather- 

 covered book. Pull the bee away and with a lens watch the 

 movements of the sting, which will remain caught in the 

 leather. Observe the spasmodic contractions of the poison 

 sac. See how long and how energetically the movements are 



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