NEMATODA FILARIIDAE 1 49 



disease in marshy country it is probably some aquatic animaL 

 The larvae are said by Manson to disappear from the peripheral 

 circulation of the dog during the day, but not to such a marked 

 extent as do the F. sanguinis hominis Lew., var. nocturna Man. 

 They were found by Galeb and Pourquier in the foetus of an 

 infested bitch, a fact which establishes the transmission of such 

 parasites through the placenta. 



Filaria sanguinis hominis nocturna. The female of this 

 parasite has been described as living in the lymphatic glands of 

 man. The embryos escape from it into the lymph, and thus 

 reach the blood. According to Manson the intermediate host is 

 the mosquito, in whose stomach the embryos undergo their larval 

 changes. When the mosquito dies the larvae escape into the 

 water, and then make their way into the alimentary canal of 

 man, where they are believed to pair, and whence the female 

 makes its way to the lymphatics. The presence of this Filaria 

 causes great functional disturbance. One of the most remarkable 

 features of it is that the larvae, which are very numerous in the 

 blood during the night, disappear during the day, and are not to be 

 found. Eecently Manson 1 has described two new varieties : F. san. 

 horn, diurna, in which the conditions of things are reversed, the 

 larvae being found by day and not by night ; and F san. horn, 

 perstans, in which the larvae occur both by day and by night. The 

 larvae are long-lived, and were found by Manson in the blood of 

 a negro who had not been in Africa, where it is endemic, for six 

 years. The same observer is inclined to associate the presence 

 of F san. horn, perstans with the fatal disease known as " sleeping 

 sickness." He also suggests that the mature form of the variety 

 diurna is the F. loa, which is not uncommon in the eyes of 

 negroes, and that its intermediate host may be one of the blood- 

 sucking flies so common on the west coast of Africa. 



The genus Ichthyonema is confined to fishes. The male is 

 very minute and the female partly degenerate. It has no anus 

 and no external opening to its generative organs. The uterus 

 fills up almost the whole of the body-cavity. I. sanguineum 

 Kud. is found encapsuled in the peritoneum of many fish. ^ c 



Hystrichis and Dispharagus are confined to birds, where they 

 occur in the oesophagus and stomach. Spiroptera reticulata 



1 "The Distribution, etc., of Filaria sanguinis hominis," Trans, of 7th Inter. 

 Congress of Hygiene, vol. i. 1892, p. 79. 



