joining _k_ and _d_ (the dart protractor) now revolves _k_ on _l_, so that _a_ is raised, by which clearly _c_ is made to approach _d_; _i.e._ the dart is sent forward, so that the barbs extend beyond the sheath and deepen the puncture. The other dart, and then the sheath, follow, in a sequence already explained, and which _G_, Fig. 195, is intended to make intelligible, _a_ representing the entrance of the sheath, _b_ the advance of the barbs, and _c_ the sheath in its second position. The barb retractor muscle is attached to the outer side of _i_, and by it _a_ is depressed and the barbs lifted. These movements, following one another with remarkable rapidity, are entirely reflex, and may be continued long after the sting has been torn, as is usual, from the insect. By taking a piece of wash-leather, placing it over the end of the finger, and applying it to a bee held by the wings, we may get the fullest opportunity of observing the sting movements, which the microscope will show to be kept up by continued impulses from the fifth abdominal ganglion and its multitudinous nerves (_n_, Fig. 194, _A_), which penetrate every part of the sting mechanism, and may be traced even into the darts. These facts, together with the explanation at page 49, will show why an abdomen separated many hours may be able to sting severely, as I have more than once experienced. [Illustration: FIG. 192.—Base of the ovipositor of _Locusta viridissima_ seen from beneath: _c′_, sheath, or outer and lower pair of stylets turned to one side to show the others; _b′_, upper and inner pair; _b″_, third or innermost, smallest pair of stylets. _A_, the same on one side, in section. The shaded parts show the muscular attachments. The muscles which extend the apparatus and are attached to ν, δ, and η, as also the membranes which unite the pieces from η; to γ with each other and the body, are removed, so that only the chitinous parts remain.—After Dewitz. ] [Illustration: FIG. 193.—Development of the sting in Bombus: _A_, _a_, 1st pair on 8th sternite; _b_, 2d inner pair forming the darts; _c_, outer pair. _B_-_E_, more advanced stages. _F_, _x_, _y_, _z_, three pairs of tubercles, the germs of the male organs. ] [Illustration: FIG. 194.—Sting of bee × 30 times: _A_, sting separated from its muscles; _ps_, poison sac; _pg_, poison gland; _5th g_, 5th abdominal ganglion; _n_, _n_, nerves; _e_, external thin membrane joining sting to last abdominal segment; _i_, _k_, _l_, and _i′_, _k′_, _l′_, levers to move the darts; _sh_, sheath; _v_, vulva; _p_, sting-palpus or feeler, with tactile hairs and nerves. _B_ and _C_, sections through the darts and sheath, × 300 times: _sh_, sheath; _d_, darts; _b_, barbs; _p_, poison-channel. _D_, end of a dart, × 200: _o_, _o_, openings for poison to escape into the wound.—After Cheshire. ] [Illustration: