Brehm observes that the male reproductive organs of the Cockroach are most nearly paralleled by those of the Mantidæ. A free penis occurs in all Orthoptera, except Acridiidæ and Phasmidæ. The male organs of the House Cricket will be found much easier to understand than those of the Cockroach. The testes are of irregular, oval figure, the vasa deferentia very long, tortuous, and enlarged towards the middle of their length. The vesiculæ seminales bear many utriculi majores et breviores. The penis is of simple form, and dilated at the end. The titillator is broad, but produced into a slender prong, which projects beyond the penis. A pair of subanal styles is found, but the unpaired hooklets are wanting or very inconspicuous. [Illustration: Fig. 103.--The Tenth Tergum reflected to show the external male organs _in situ_. _T^{10}_, tenth tergum; _p_, podical plates; _A-F_, as in fig. 102; _S_, sub-anal styles. × 8.] Very little is known about the act of copulation among Cockroaches, and the opportunities of observation are few. The following account is given by Cornelius (_loc. cit._, p. 22):-- “The male and female Cockroaches associate in pairs, the females being generally quiet. The male, on the contrary, bustles about the female, runs round her, trailing his extended abdomen on the ground, and now and then raises his wings. If the female moves away, the male stops the road. At last, when the female has become perfectly still, the male goes in front of her, brings the end of his abdomen towards her, then moves backwards, and pushes his whole length under the female. The operation is so rapid that it is impossible to give an exact account of the circumstances. Then the male creeps out from beneath the female, raises high both pairs of wings, depresses them again, and goes off, while the female usually remains quiet for some time.” CHAPTER X. DEVELOPMENT. _SPECIAL REFERENCES._ RATHKE. Zur Entwickelungsgesch. der _Blatta germanica_. Meckel’s Arch. of Anat. u. Phys., Bd. VI. (1832). BALFOUR. Comparative Embryology, 2 vols. (1880–1). GRABER. Insekten, Vol. II. (1879). LUBBOCK. Origin and Metamorphoses of Insects (1874). KOWALEWSKY. Embryol. Studien an Würmern u. Arthropoden. Mém. Ac. Petersb. Sér. VII., Vol. XVI. (1871). WEISMANN. Entw. der Dipteren. Zeits. f. wiss. Zool., Bde. XIII., XIV. (1863–4). METSCHNIKOFF. Embryol. Studien. an Insecten. Ib., Bd. XVI. (1866). BÜTSCHLI. Entwicklungsgeschichte der Biene. Ib., Bd. XX. (1870). BOBRETZKY. Bildung d. Blastoderms u. d. Keimblätter bei den Insecten. Ib., Bd. XXXI. (1878). NUSBAUM. Rozwój przewodów organów pteiowych u owadów (Polish). Kosmos. (1884). [Development of Sexual Outlets in Insects.] ---- Struna i struna Leydig’a u owadów (Polish). Kosmos (1886). [Chorda and Leydig’s chorda in Insects.] _The Embryonic Development of the Cockroach._[174]