TRICHINELLID^E 419 



In cases of infection with 0. volvulus larvae have been found by 

 Ouizilleau, Fiilleborn, and Simon in lymph glands, and in the finger 

 blood if considerable pressure is used so as to squeeze lymph out 

 of the tissues. They are slieathless, and the following are the 

 dimensions in ordinary dried films: Length, 274^; nerve ring, 

 23-7 per cent. ; Gi cell, 69*6 per cent. ; end of last tail cell, 96*3 per 

 cent. The dimensions of larvae of 0. volvulus taken from the uterus 

 and prepared in the same way are: Length, 224^5 //,; nerve ring, 

 24*3 per cent. ; Gi cell, 68-9 per cent. ; end of the last tail cell, 

 95*5 per cent. In all probability the larvae in the glands and blood 

 are those of 0. volvulus. 



According to the natives, the tumours may last indefinitely and 

 never ulcerate. Some old patients told Brumpt that their tumours 

 had been present since childhood. Probably Onchocerca volvulus, 

 like some other Filariidce, may live for many years. 



0. volvulus occurs in various parts of West Africa : Gold Coast, 

 Sierra Leone, Dahomey, Lagos, Cameroons. Brumpt, on the banks 

 of the Welle between Dongon and M'Binia (Belgian Congo), found 

 about 5 per cent, of the riverine population affected. 



Family. Trichinellidae, Stiles and Crane, 1910. 

 Sub-family. Trichurinae, Ransom, 1911. 



Male with a single long spicule, with sleeve-like sheath. One 

 ovary. Eggs with an opening at each pole closed by a plug-like 

 operculum. Eggs hatch on being swallowed by a new host. Genera : 

 Trichuris, Capillaria. 



Genus. Trichuris, Roderer and Wagler, 1761. 



Syn. : Trichocephalus, Goeze, 1782 (nee Trichiurus, L., 1758); Mastigodes, 



Zeder, 1803. 



The anterior part of the body is very long and thread-like : the posterior, much 

 shorter part, is thicker, rounded posteriorly, and the anus is terminal. The males 

 have the posterior extremity spirally rolled ; the vulva is situated at the commence- 

 ment of the posterior part of the body. The Trichocephali live in the large intestine 

 of mammals, the caecum by predilection ; their development is direct, infection occurs 

 through the ingestion of embryo-containing eggs. 



Trichuris trichiura, Linnaeus, 1761. 



Syn. : Trichocephahis trichiurus, L., 1771 ; Ascaris trichiura, L., 1771 ; 

 Trichocephalus hominis, Schrank, 1788; Trichocephalus dispar, Rud., 1801. 



The male measures 40 to 45 mm. in length, the spicule is 

 2*5 mm. long, its retractile sheath is beset with spines. The female 

 measures 45 to 50 mm. in length, of which two-fifths appertain 



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