ORGANS OF SEX. The continuation of the species is effected in Insects by means of two sexes, each endowed with special reproductive organs. It has been stated that there are three sexes in some Insects—male, female, and neuter; but this is not correct, as the so-called neuters are truly sexed individuals,—generally females,—though, as a rule, they are not occupied with the direct physiological processes for continuing the species. The offspring is usually produced in the shape of eggs, which are formed in ovaries. These organs consist of egg-tubes, a cluster of which is placed on each side of the body, and is suspended, according to Leydig[61] and others, to the tissue connected with the heart by means of the thread-like terminations of the tubes. {138}[Illustration: FIG. 74.—Sex organs of female of _Scolia interrupta_ (after Dufour); _a_, egg-tubes; _b_, oviducts; _c_, poison glands; _d_, duct of accessory gland (or spermatheca); _e_, external terminal parts of body.] The number of egg-tubes varies greatly in different Insects; there may be only one to each ovary (_Campodea_), but usually the number is greater, and in the queen-bee it is increased to about 180. In the Queens of the Termitidae, or white ants, the ovaries take on an extraordinary development; they fill the whole of the greatly distended hind-body. Three thousand egg-tubes, each containing many hundred eggs, may be found in a Queen Termite, so that, as has been said by Hagen,[62] an offspring of millions in number is probable. There is considerable variety in the arrangements for the growth of the eggs in the egg-tubes. Speaking concisely, the tubes may be considered to be centres of attraction for nutritive material, of which they frequently contain considerable stores. Next to the terminal thread, of which we have already spoken, there is a greater or smaller enlargement of the tube, called the terminal chamber; and there may also be nutriment chambers, in addition to the dilatations which form the egg-chambers proper. Korschelt[63] distinguishes three principal forms of egg-tubes, viz. (1) there are no special nutriment chambers, a condition shown in Figure 74; (2) nutriment chambers alternate with the egg-chambers, as shown in our Figure of an egg-tube of _Dytiscus marginalis_; (3) the terminal chamber takes on an unusual development, acting as a large nutriment chamber, there being no other special nutriment chambers. This condition is found in _Rhizotrogus solstitialis_. The arrangements as to successive or simultaneous production of the eggs in the tubes seem to differ in different Insects. In some forms, such as the white ants, the process of egg-formation (oogenesis) attains a rapidity that is almost incredible, and is continued, it is said, for periods of many months. There is no point in which Insects differ more than in that of the number of eggs produced by one {139}female. The egg-tubes are connected