[170] The spermatocysts are peculiar to Insects and Amphibia. They arise by division of the spermatospores, or modified epithelial cells, and form hollow cysts, within which sperm cells (or spermatoblasts) are developed by further division. The sperm cells are usually placed radiately around the wall of the spermatocyst. They escape by dehiscence, and are transformed into spermatozoa.
[171] Huxley, Anat. Invert. Animals, p. 416.
[172] The term “accessory gland,” used by Huxley and others, is already appropriated to glands which we believe to be represented by the utricles of the Cockroach, and which have only a general correspondence with the gland in question.
[173] Similar organs, forming a male genital armature, have been described in various Insects. See Burmeister, Man. of Entomology, p. 328 (Eng. Transl.); Siebold, Anat. of Invertebrates; Gosse in Linn. Trans., Ser. 2, Vol. II. (1883); Burgess on Milk-weed Butterfly, Ann. Mem. Bost. Soc. Nat. Hist.; &c.
[174] In the following description it is to be understood that the observations have been made upon Blatta germanica, except where P. orientalis is expressly named.
[175] Fertilisation consists essentially in the union of an egg-nucleus (female nucleus) with a sperm-nucleus (male nucleus). From this union the first segmentation-nucleus is derived.
[176] Balfour, Embryology, Vol. I., p. 337.
[177] Q. J. Micr. Sci., Vol. XXIV., page 596 (1884).
[178] Kowalewsky in Hydrophilus, Graber in Musca and Lina, Patten in Phryganidæ, myself in Meloe, &c.
[179] Biolog. Centrablatt. Bd. VI., No. 2 (1886).