ANATOMY AND PHYSIOLOGY 



55 



(Fig. 81, B), and the ventral two form the darts, each of which has ten 

 barbed teeth behind its apex, which tend to prevent the withdrawal of 

 the sting from a wound. The action of the sting, as described by Che- 



FIG. 79. Ovipositor of Locusta. A, lateral aspect; B, ventral aspect; C, transverse sec- 

 tion; c, cerci; d, dorsal valve; i, inner valve; v, ventral valve. The numbers refer to ab- 

 dominal segments. After KOLBE and DEWITZ. 



shire, is rather complex. Briefly, the sheath serves to open a wound and 

 to guide the darts; these strike in alternately, interrupted at intervals 

 by the deeper plunging of the sheath (Fig. Si, A). The poison of the 

 honey bee is secreted by two glands, one acid and 

 the other alkaline. The former (Fig. 82) consists 

 of a glandular region which secretes formic acid, of 

 a reservoir, and a duct that empties its contents 

 into the channel of the sheath. The alkaline gland 

 also opens into the reservoir. It is said that both 

 fluids are necessary for a deadly effect ; and that in 

 insects which simply paralyze their prey, as the 

 solitary wasps, the alkaline glands are functionless. 

 Male Genitalia. The penis may be hollow or 

 else solid, and in the latter case the contents of 

 the ejaculatory duct are spread upon its surface. 

 Morphologically, the male gonapophyses correspond to those of the 

 female. The penis (Fig. 83) represents the two inner valves of the ovi- 



FIG. 80. Cross-sec- 

 tion of the ovipositor of 

 Sirex. c, channel; d, 

 d, dorsal valves; i, 

 united inner valves; v, 

 v, ventral valves. After 

 TASCHENBERG. 



