ANATOMY AND PHYSIOLOGY 



described by Cheshire, is rather complex. Briefly, the sheath 

 serves to open a wound and to guide the 

 darts; these strike in alternately, inter- 

 rupted at intervals by the deeper plung- 

 ing of the sheath (Fig. 81, A). The 

 poison of the honey bee is secreted by 

 two glands, one acid and the other alka- 

 line. 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 gona- 



Extremity of abdomen 

 of a male beetle, Hy- 

 drophilus, ventral aspect. 

 g, genitalia; p, penis; 

 vi > v 2 > pairs of valves 

 enclosing the penis; 6-9, 

 sterna of abdominal seg- 

 ments. After KOLBE. 



FIG. 84. 



Extremity of abdomen of a 



male May fly, Hexagenia varia- 



bilis, ventral aspect. c, c, c, 



cerci; cl, cl, claspers; i, i, in- 

 tromittent organs. 



of the abdomen. 



pophyses correspond to those of the 

 female. The penis (Fig. 83) rep- 

 resents the two inner valves of the 

 ovipositor and is frequently enclosed 

 by one or two pairs of valves. In 

 Ephemerida the two inner valves 

 are partly or entirely separate from 

 each other, forming two intromit- 

 tent organs (Fig. 84). 



In male Odonata, the ejaculatory 

 duct opens on the ninth abdominal 

 segment, but the copulatory organ is 

 placed on the under side of the sec- 

 ond segment, to -which the spermato- 

 zoa are transferred by the bending 

 At copulation, the abdominal claspers of the 



