356 NEMATHELMINTHES. 



times with a horny oral capsule, with four prseanal pairs of papillse, to which 

 an unpaired papilla may be added, with two unequal spicula or with simple 

 spiculum. 



A'ilaria 0. Fr. Mull. With small mouth and narrow oesophagus. This 

 species, which is sometimes destitute of papillae, lives outside the viscera, 

 usually in connective tissue, frequently beneath the skin (divided by Diesing 

 into numerous genera). F. (Dracunculus) mcdincnsis* Gmel. the Guinea 

 worm, in the subcutaneous cellular tissue of Man in the Tropics of the Old 

 World, reaches a length of two feet or more. The head is provided with two 

 small and two larger papillae. The female is viviparous, and without sexual 

 opening. The male form is unknown. The worm lives in the connective 

 tissue between the muscles and beneath the skin, and after reaching sexual 

 maturity, occasions the formation of an abscess, with the contents of which 

 the embryos escape to the exterior (fig. 287). It has lately been proved 

 (Fedschenko) that the embryos of Filaria migrate into a Cyclops and there 

 undergo an ecdysis. Whether they are then (in the body of the Cyclops) 

 introduced into man in his drinking water, or whether they first escape and 

 copulate in a free state, is not known. F. immitis lives in the right ventricle 

 of the dog, and is very abundant in East Asia. It is viviparous. The 

 embryos pass directly into the blood, where, however, they do not undergo their 

 further development. Similar young Ha3matozoa are also found in the blood 

 of man in the Tropics of the New and Old Worlds (F. sanguinis Jwminis, 

 F. Bancrafti). Since these animals are also found in the urine, their appear- 

 ance seems to have an tetiological connection with hsematuria. In the East 

 Indies, young Filaria also live in the blood of the street dog, and would seem 

 to be related to the brood of Filaria sanguinolenta, since, according to Lewis, 

 knotty swellings on the aorta and oasophagus are invariably found with these 

 Filaria. F. papttloxa Hud. in the peritoneum of the horse. F. loa Guyot., in 

 the conjunctive of negroes on the Congo. F. laMalis Pane. Only once observed 

 at Naples. An immature Filaria described as Filaria lentis (ocnli humani) 

 has been found in the human capsula lentis. 



Fam. Mermithidae. Aproctous Nernatodes, with very long filiform body, and 

 six oral papillae. The male caudal region is broad, and is provided with two 

 spicula and three rows of numerous papillae. They live in the body cavity of 

 insects, and escape into the damp earth, where they attain sexual maturity 

 and copulate. Mcrmis nigrcscens Duj., was the occasion of the fable of the 

 worm rain. M. alMcans v. Sieb. v. Siebold established by experiment the 

 migration of the embryos into the caterpillars of Tinea cvonynwlla. Sphcerularia 

 boinbi Leon Duf. 



Fam. Gordiidae. Body elongated and filiform. Without oral papillse and lateral 

 lines, with a ventral cord. The mouth and anterior region of the alimentary 

 canal is obliterated in the adult state. The testes and ovaries are paired and 

 open to the exterior with the anus near the hind end of the body. Uterus 

 unpaired, with receptaculum seminis. The male caudal region is forked, and is 

 destitute of spicula. In the young stage they live in the body cavity of predatory 

 insects, and are provided with a mouth. At the pairing time they pass into the 

 water, where they become sexually mature. The embryos, which are provided 

 with a circle of spines, bore through the egg-membranes and migrate into 

 Insect larvaa (Chironomus-larvte, Epliemerida:}, and there encyst. Water 



* Compare H. C. Bastian, "On the Structure and Nature of the Dracunculus," 

 Trans. Linn. Society, vol. xxiv., 1863. Fedschenko I. c. 



