560 MEDICAL ENTOMOLOGY 



narrower and unite with one another. From their point of junction 

 the common channel is continued backwards to the penis as a fine 

 efferent duct. In fresh dissections the receptacula are very cons-' 

 picuous on account of their translucent appearance and their slight 

 greenish tinge ; the testes lie in the anterior segments of the abdomen, 

 and are embedded in fat body, from which they are not easy to remove. 



The female organs of reproduction consist of ovaries, oviducts, a pair 

 of accessory glands, and a common oviduct. Each ovary consists of 



five ovarian tubes, usually divided into three follicles, 

 The Female Organs . ,. . . , , . , 



which are distinctly separated from one another by an 



interval in which the tube is much constricted. In the mature ovary 

 (Plate LXXI, fig. 1) at least one of the lowest follicles on each side 

 contains a mature or nearly mature egg, while the other follicles of the 

 same rank contain ova at various stages of development, some being 

 only a quarter or a third the size of the largest. The follicles of the 

 second row are always small, and those of the third little more than mere 

 swellings on the tube ; it is to be noted, however, that even in these 

 small chambers there is a considerable variation in size. The tube is 

 continued forwards from the smallest follicles as a delicate apical fila- 

 ment, all the filaments converging together in the usual manner. At the 

 lower end of the lowest follicle of each tube the separate tubes, after a 

 short independent course, are collected together and unite to form a 

 duct common to the ovary of the side. The accessory glands are 

 situated on and partly conceal this portion of the duct ; each is a large 

 and irregularly triradiate structure, resembling more than anything ele 

 the three-legged symbol of the Isle of Man ; one limb is directed 

 forwards, one backwards, and the other outwards, the whole being 

 closely adherent to the duct. The commencement of the common 

 oviduct lies between them, and from this point the duct passes straight 

 backwards to the genital opening ; it is of rather large size, and has much 

 muscular tissue in its wall. 



The long duration of copulation in the lease, and the frequent 

 repetition of the act, are of special interest in view of the absence of a 

 receptacle for the sperms in the female, and the relatively large size 

 of the receptaculum in the male. It will be noticed that the conditions 

 found in the ovaries, in regard to the maturity of the eggs in the lowest 

 row of follicles, are in accordance with the observed habits of oviposition. 

 A departure from the type of reproduction usual in insects is frequently 

 to be observed in association with the parasitic habit ; the bed bug is a 

 striking case in point. 



