DIVISION OF ENTOMOLOGY. 9 



lohed projection, (\vw, Fig. 3) the lobes of which are turned toward 

 the bulb. 



It will thus be seen that the dorsal and ventral walls of the penis 

 tube bear distinguishing characters. This is equally true after the 

 organ becomes evaginated, as it does in the act of copulation. In that 

 act it is generally believed that the whole tube of the penis turns out 

 through the genital slit into the vagina of the queen. That is, the 

 pneumophyses evaginate into the pouches of the bursa copulatrix — the 

 pinnate lobe and the bulb everting in turn and pressing deeper within 

 the vagina. It is well known that if a flying, excited drone is caught 

 and held between the thumb and finger or in the hollow of the hand, 

 the copulatory organ will sometimes be suddenly everted with force. 

 The abdomen contracts rigidly to less than half its former size as the 

 organ is expelled, and the insect quickly dies. Also, as a drone is held 

 betw'een the thumb and finger, pressure on the abdomen (from before 

 backward) may often be used successfully to fully expel the organ — 

 especially when the tracheal system is well filled with air. Cheshire, 

 at "E" Fig. 41 (citation) and Michaelis,* Plate XXVI, have both given 

 illustrations of the drone organ in the fully extruded condition. In 

 order to help show the relation of the structural parts in the extruded 

 penis, an illustration of the same is also given herewith, Fig. 4. Pres- 

 sure, brought to bear upon the contents of the drone's abdomen through 

 the contraction of the abdominal wall muscles, normally starts the 

 process of evagination. As the abdomen contracts, the confined air 

 in the vesicles of the tracheal system becomes compressedf ; the blood 

 in the body cavity, however, moves freely to the area of least resist- 

 ance — to the base of the penis. In that moment the crumpled tubular 

 penis wall, next the genital slit, is pushed through the slit and swells 

 out behind — expanded with blood. Eversion has begun, and with it the 

 small tracheae at the base of the penis are stretched lengthwise to the 

 limit. They yield and break as the large, ventral, quadrangular, spine- 

 covered plate rolls out and, thus, they release the compressed air of 

 the tracheal vesicles within the evaginating fold of the partly protruded 

 penis. Instantly, the pneumophyses dart forth and curve downward in 

 the form of two hollow white horns, filled with air and Mood. The 

 cross striped ventral ridges and the dorsal triangular plate appear. 

 Each everting portion of the penis draws after it the next anterior 

 portion down through the part of the tube already evaginated until, 

 finally, the doubly pinnate-lobed appendagej begins to show. Then 

 the bulb snaps out and the process of evagination stops at the point 

 where the former anterior end of the bulb — now the distal end of the 

 extruded organ — connects with the narrow ejaculatory duct. The 

 opening of that duct may be seen in the upturned tip of the fully ex- 

 truded penis (o. Fig 4), and from there through the lumen of that 

 organ the slender ejaculatory duct itself may be traced to where it 

 still attaches to the accessory glands at the posterior end of the ab- 

 domen — sometimes the ends of the paired organs are found partially 

 forced into the distended base of the penis. The position of the ejacu- 



*Michaelis, Georpr. Bau und Entwicldung des Mannllchen Begattungs — apparates der Honig- 

 biene. Zeitschr. Wiss. Zool. LXVII, 1900, pp. 439-60. 



tDJathchenko, Sophie, 1906 in Ann. de Ij'Institut Agron. de Moscou, ligures the closing ap- 

 paratus of the stigmata! tracheae of the bee. 



JThis appendage evaginates normaHy just as the bulb snaps. 



