650 



NEMA THELMINTHES 



It is found in Sierra Leone, Gold Coast, and Dahomey; but on 

 the Welle, between Dongon and M'Bini, it is said to occur in 5 per 

 cent., and on the Itumburi, between Bonta and Idembo, in i per 

 cent, of the population. It has not been recorded as far south as 

 the Congo. Theze has recorded three cases from Dutch Guiana, 

 and Leiper has recently confirmed its occurrence in Guatemala, 

 where, according to Robles, the infection is very common, 



Morphology. — -The male worm has a white filiform body, slightly 

 attenuated at the ends, covered with a transversely striated cuticle, 

 measuring 30 to 35 millimetres in length and 0-14 millimetre in 

 breadth. 



The head is rounded, the mouth unarmed, the alimentary canal 

 straight and undifferentiated, the anus subterminal 0-049 niilli- 

 metre in front of the posterior end. Other canals are reported, 

 which probably belong to the generative and extretory systems. 



The tail is strongly recurved, and somewhat flattened on its 

 concave aspect. Brumpt reports three pairs of papillae on each side 

 of the anus and three pairs of post-anal papillae. There are two 

 unequal spicules, the larger 177 and the smaller 82 /a, in length. 



Fig. 278. — -Microfilaria of Onchocerca volvulus Leuckart. 

 (After Fulleborn.) 



The female is longer and thicker than the male, measuring 60 to 

 70 millimetres in length and 0-36 millimetre in breadth. The 

 cuticular striations are ring-like and well marked. The tail is 

 recurved. The uterus is seen full of eggs and larvae, and the vulva 

 is 0*76 millimetre from the anterior end. 



Life-History,^ — -The worm is said to lie in a lymphatic, whicli 

 becomes inflamed, and a perilymphangitis causes a condensation 

 of connective tissue, in which males and females are embedded, 

 leaving the posterior end of the male and the anterior end of the 

 female free in the lymph space. The embryos pass out of the uterus 

 into this space, where they can be found 250 to 300 ^ in length, and 

 5 to 6 in breadth, with a rounded head and a body which tapers 

 during the last fifth, and terminates in a pointed tail. There is no 

 sheath. The anterior V-spot is clearly seen. The microfilaria have 

 not been seen in the blood, and their further development is quite 

 unknown. 



The embryos have recently been found in the blood, and Brumpt 

 is inclined to think that the further development will be in a tsetse- 

 fly. The adults live for years in the human body. 



