518 MEDICAL ENTOMOLOGY 



the mosquito, by the elastic recoil of the membrane. There are no 

 muscles which could force the piston rod forwards. 



The salivary pump is by no means easy to find or to dissect out, and 

 was not described by Landois. It is best seen in longitudinal sections. 



The organs of reproduction in the bed bug present many very re- 

 markable features, both as regards their structure and function. The 

 whole process of reproduction is carried on in a highly 



Reproductive sys- abnormal manner, for the sperms, instead of being 



tern (Plate LXV) . , , , , , . .... 



destined solely for the fertilization of the eggs, prob- 

 ably also contribute to the nourishment of the pregnant female. The 

 subject is very obscure, and must remain so until a comprehen- 

 sive study of the development of the parts is undertaken ; the following 

 account is offered with reserve, as an indication of the nature of the 

 problem rather than an explanation. 



The male organs (Plate LXV, fig. 1) conform generally to the ordinary 

 type, though they differ markedly in appearance from those so far 



described. The testes are pyramidal bodies, the broad 

 The male organs , , . . . .. . , , 



end of each being directed outwards and forwards, the 



narrow apex leading to the vas deferens. Each testis is made up of 

 seven wedge-shaped lobes, the narrow end of each of which reaches to the 

 commencement of the vas, while the broad ends lie side by side on the 

 anterior surface of the organ. The lobes are separated from one another 

 by delicate fibrous septa, which extend.to the external capsule of the gland, 

 producing indentations on the surface where they fuse with it. At the 

 posterior end of each testis there is a small isolated spherical lobe, 

 closely attached to the commencement of the vas, without a stalk. This 

 is not figured or described by Landois in Citnex lecttilarius, but is of 

 constant occurrence in rotundatiis. It may be an accessory gland, 6r 

 a degraded lobe of the testis. The vas deferens is relatively short and 

 stout, being not more than twice the length of the testis. It is narrow- 

 in the upper part, but widens out in a spindle-shaped manner towards 

 its lower end. In the fresh condition it has a greenish yellow colour, 

 and is translucent. According to Landois it is frequently distended 

 with sperms. 



The accessory glands (Plate LXV, fig. 2) are situated at the lower end 

 of the vasa. On each side there is a small branched gland consisting 

 of a number of tubules of varying length but of uniform diameter, 

 irregularly arranged. This opens by a short duct into a pear-shaped 

 chamber, which probably acts as a reservoir for the secretion of the 

 gland. It is placed in close apposition to the end of the vas of its 



