The male reproductive system is illustrated schematically in side view in figure 3, with the right-hand members of the paired structures not shown. Its principal paired structures are testes, vasa deferentia, and mucous glands. The ejaculatory duct and penis are single structures. In a young drone the testes are very large, slimy appearing organs that occupy almost the entire upper half of the abdomen. They gradually shrink to small greenish-yellow structures in the sexually mature done. A testis consists of small tubules which empty into a chamber at the end of the vas deferens. The vas deferens has a coiled section where it joins the testis and a long enlarged section, the seminal vesicle, which joins and empties into the lower end of the corresponding mucous gland. The two mucous glands unite at their lower ends into the narrow ejaculatory duct which leads to the penis.

The sperm cells go through development in the tubules of the testes and then pass into the vesicles where they remain until ejaculated. In the meantime the testes shrink.

The seminal vesicles have muscular walls and are lined with secretory cells that provide nourishment for the sperm. At 3 to 4 days of age a few sperm are already in the seminal vesicles, and at 4 to 5 days there are about 5 million and this increases to 10 to 11 million at 8 days. It is very important that drones receive proper care during this period. Sperm obtainable at any age are usable in artificial insemination; however, it is best to wait until all sperm have had a chance to mature. This is considered to be about 12 days of age. There seems to be no deterioration of sperm as aging continues.

The mucous glands also have muscular walls with secretory cells. As the drone matures sexually these glands become distended and white from the amorphous white mucus secreted into the lumen of the gland.

Figure 2. -Sting chamber of queen properly opened for insemination: DPO, opening of bursal pouches; DP, dorsal plate; QH, queen holder; ST, sting; STH, sting hook; VF, valvefold; VH, ventral hook; VO, vaginal orifice; VP, ventral plate.

Figure 3. -Male reproductive organs in approximately their natural position in the abdomen. The right-hand members of the paired organs (testes, vasa deferentia, and mucous glands) are not shown.

The penis is a soft membranous sack with a number of bizarre processes and hairy areas. At its inner end it is enlarged into the bulb and provided with a pair of hard comma-shaped brown plates. The bulb is filled with a clear liquid which dilutes the sperm during ejaculation.

In mating the penis turns inside out to the outside of the body, pulling the ejaculatory duct through itself (fig. 4). This eversion is brought about by the simultaneous contraction of all the muscles of the abdomen. Ejaculation takes place during this eversion. A peristaltic contraction of the muscles of the seminal vesicles, beginning at their anterior ends, squeezes the sperm out through the ejaculatory duct; then the muscles of the mucous gland contract to push the mucus after the sperm into the bulb. These processes can be started by a number of artificial stimuli such as decapitation, pressure on the abdomen, chloroform fumes, or electric shock. When started in this way, the eversion usually stops at the stage illustrated in figure 4, A. With further pressure on the abdomen, which must be applied to complete the eversion, the bulb passes on through a narrow section of the penis with a jerk, the points of the comma-shaped plates appear at the very end of the everted penis, and the semen and mucus are ejected from the bulb to the outside (fig. 4, B). In natural mating the transfer of semen to the queen is thought to take place at this stage. Under the artificial conditions of mechanical pressure on the abdomen, the eversion often proceeds still further until the bulb and its plates are turned completely inside out (fig. 4, C). Sometimes the internal pressure becomes so great that the penis explodes. In the technique of inducing eversion and ejaculation artificially, the aim is to stimulate muscle contraction and not to force the action. The sperm and mucus then come out in natural sequence with minimum mixing of the two. It is impossible to obtain a normal ejaculation by mechanical means alone.

Figure 4. -Stages of the eversion of the drone's penis:. 4, Partial eversion usually encountered after initial stimulation; B, a more complete eversion usually obtained by squeezing the abdomen, with semen and mucus exposed; and C, a fully everted penis (semen and mucus not shown).

The semen is made up of the sperm plus liquids from the seminal vesicles and the bulb. The sperm are in bundles, giving the semen a cloudy or mottled appearance. This appearance together with its cream color makes semen easily distinguishable from the homogeneous snow-white mucus. The semen becomes darker and contains more sperm as the drone ages; the best quality semen of dark-cream color, not mixed with mucus, is obtained from drones at least 12 days old. The quality does not seem to deteriorate with further aging.