This sack was discovered and its use suggested by Malpighi as early as 1686, but its function was not fully demonstrated till 1792, when the great anatomist, John Hunter, showed that in copulation this was filled. The ovaries are multitubular organs. In some insects there are but very few tubes--two or three; while in the queen bee there are more than one hundred. In these tubes the ova or eggs _grow_, as do the sperm cells in the vesicles of the testes. The number of eggs is variable. Some insects, as the mud-wasps, produce very few, while the queen white-ant extrudes millions. The end of the oviduct, called the ovipositor, is wonderful in its variations. Sometimes it consists of concentric rings, like a spy-glass which may be pushed out or drawn in; sometimes of a long tube armed with augers or saws of wonderful finish, to prepare for eggs; or again of a tube which may also serve as a sting. Most authors state that insects copulate only once, or at least that the female only meets the male but once. My pupil, Clement S. Strang, who made a special study of the structure and habits of bugs during the past season, noticed that the squash-bugs mated many times. It would be interesting to know whether these females possessed the spermatheca. In some cases, as we shall see in the sequel, the male is killed by the copulatory act. I think this curious fatality is limited to few species. To study viscera, which of course requires very careful dissection, we need more apparatus than has been yet described. Here a good lens is indispensable. A small dissecting knife, a delicate pair of forceps, and some small, sharp-pointed dissecting scissors--those of the renowned Swammerdam were so fine at the point that it required a lens to sharpen them--which may also serve to clip the wings of queens--are requisite to satisfactory work. Specimens put in alcohol will be improved, as the oil will be dissolved out and the muscle hardened. Placing them in hot water will do nearly as well, in which case oil of turpentine will dissolve off the fat. This may be applied with a camel's-hair brush. By dissecting under water the loose portions will float off, and render effective work more easy. Swammerdam, who had that most valuable requisite to a naturalist, unlimited patience, not only dissected out the parts, but with small glass tubes, fine as a hair, he injected the various tubes as the alimentary canal and air-tubes. My reader, why may not you look in upon those wondrous beauties and marvels of God's own handiwork--nature's grand exposition? Father, why would not a set of dissecting instruments be a most suitable gift to your son? You might thus sow the seed which would germinate into a Swammerdam, and that on your own hearth-stone. Messrs. Editors, why do not you, among your apiarian supplies, keep boxes of these instruments, and thus aid to light the torch of genius and hasten apiarian research? TRANSFORMATIONS OF INSECTS.