342 The Parasites of the Cockroach. 



development ; and individuals apparently dead may be seen 

 crowded with eggs ready to issue from the opening which exists 

 near the centre of the body. The male is provided with 

 secreting organs, a receptacle, and " ductus ejaculatorius." 



The fecundation of the ova takes place within the body of the 

 female, and they undergo a certain amount of development in 

 the intestine of the cockroach, but appear to be passed out of 

 the insect's body and again swallowed before attaining maturity, 

 although they do not undergo any larval stages, but are born 

 with their parents' form and appearance. 



No eyes or special organs of sense exist in the Nematodes, 

 though the existence of an obscure nervous system has been 

 ascertained. No circulatory or respiratory system has been dis- 

 covered in Anguillula or any allied genera. The vinegar eels 

 and paste-worms are non-entozoic members of the genus 

 Anguillula, and live entirely independent of other organisms. 

 With these exceptions, however, the Nematodes are almost all 

 parasitic in the intestines of insects, Crustacea, and other 

 animals. 



The order Nematoidea is ranked, under the class Scolecida, 

 with the Tapeworms (Tceniada), Flukes (Trematoda) , and Hair- 

 worms (Gordiacea), and some others. Of the last order named 

 the parasite we now have to describe is a member. The 

 Gordius orientalis is a whitish-looking worm, two inches or 

 more in length, and is only occasionally found in the cockroach 

 (Fig. 16). It inhabits the abdominal cavity. The mouth and 

 intestinal canal are very difficult to trace in these animals, as 

 they exist here only in a rudimentary state. To complete their 

 development, the Gordii pass out of the insect they infect, and 

 consummate their existence in moist earth or water. The Gor- 

 diaceas infest nearly every species of insect, and sometimes are so 

 numerous in certain spots, after leaving their " late proprietors," 

 that stories of worm-rains, and similar fancies, have been ori- 

 ginated. The Gordius of the Blatta is small compared to that 

 which inhabits the violet-beetle (an insect scarcely an inch long), 

 which measures sometimes no less than fifteen inches from head 

 to tail, whilst other species are sometimes three feet in length. 

 The Gordius orientalis is not so interesting a subject for study as 

 the Anguillula macrura, on account of its immature condition ; 

 but a little searching in the damper parts of cellars and cup- 

 boards might bring some of the mature individuals to light, and 

 the anatomy of this parasite could then be deciphered. In 

 those Gordiaceee which have been examined, the generative 

 apparatus is much the same as that of the Nematoidea ; but the 

 males are somewhat different, the extremity of the body being 

 bifid, and the reproductive outlet being placed here. 



To any one with a good microscope, and some patience and 



