S48 REPORT OF THE HARVARD AFRICAN EXPEDITION 
muddy pools, in crab-holes and in the water gathered by the leaves of water- 
lettuce, Pistia stratiotes Linnaeus. It appears to be as widely distributed as 
C. grahamii, being known at present from Sierra Leone, the Gold Coast, Cam- 
eroon, the Lower Belgian Congo, and the coast of Tanganyika Territory (Dares- 
salaam). 
In recent years it has been shown that C. austenz is the intermediary host of 
Acanthocheilonema perstans (Manson), a parasitic roundworm of man, which has 
also been reported from chimpanzee and gorilla. This parasite, also known as 
Filaria perstans or Dipetalonema perstans, lives as adult in the connective tissue, 
especially of the mesentery. It is very common throughout tropical Africa 
(about 92 per cent of the native population are infected in British Cameroon) 
and it has also been reported from British Guiana, and North Africa (Algeria). 
The embryos, or microfilariae, are found in the peripheral blood both by day 
and by night. The parasite usually causes no pathological symptoms in man. 
A. Hodges (1902, Jl. Trop. Med., V, pp. 293-300), in Uganda, found that these 
embryos undergo a partial development in certain mosquitoes, such as A édes 
aegypti (Linnaeus), Aédes vittatus (Bigot) ( = sugens of authors), Anopheles 
gambiae Giles ( = costalis of authors), Taeniorhynchus fuscopennatus Theobald, 
Mansonioides uniformis Theobald, and Panoplites sp.; but when the larvae reach 
the thoracic muscles they do not develop further. Fiilleborn (1908, Arch. 
Schiffs-u. Tropenhyg., XII, Beiheft 9, p. 34) also observed a partial develop- 
ment of the embryos in Anopheles maculipennis Meigen, in Germany. None of 
these mosquitoes, however, can act as true intermediary hosts. 
The true life-history was elucidated by N. A. D. Sharp, who carried on experi- 
ments with Culvcoides austenz, in British Cameroon. He found that this midge 
occurs during the wet season only; it feeds principally at night between 10 Pp. m. 
and 2 a.m. and bites in the dark only. If the midge is allowed to bite a man 
having microfilariae of A. perstans in the peripheral circulation, the embryos 
develop within six hours after ingestion into larvae lying either in the stomach 
wall or in the fat body of the insect. These larvae gradually change in appear- 
ance as they migrate to other tissues. They reach the muscles of the thorax about 
twenty to thirty hours after ingestion, and the head and neck of the fly by the 
seventh day. Soon afterward they travel to the proboscis, where they lie in the 
labrum-epipharynx and eventually burst through the wall of the labrum after 
bulging it out of the proboscis. They emerge from the labrum on the eighth to 
tenth day after ingestion. At Mamfe, Cameroon, about seven per cent of the 
wild C. austeni were found infected with this worm.' 
A third species of Culicoides, C. inornatipennis (Austen), has been found in 
the Marungu Plateau (alt. 1,950 m.) of Katanga, by J. Schwetz (1927, Bull. 
Soc. Path. Exot. Paris, XX, p. 190). 
1 Sharp, N. A. D. 1927. ‘Development of Microfilaria perstans in Culicoides grahami: a preliminary 
note.’ Trans. Roy. Soc. Trop. Med. Hyg., XXI, 1, p. 70. 4 
1928. ‘Filaria perstans; its development in Culicoides austeni.’ Trans. Roy. Soc. Trop. Med 
Hyg., XXI, 5, pp. 371-396, 2 Pls. } 
