400 ANIMAL PARASITES. 



gate itself further, there, or to have an infectious action upon the 

 vicinity. But even in the hot zone it does not occur everywhere, 

 but only in particular districts, like all the Helmintha, and is 

 entirely wanting in certain places in affected countries, as, for 

 instance, in Gambia, Angola, Coulabah, &c. Particularly noto- 

 rious places are Senegal. Gaboon, the East Indies, Bombay, 

 the peninsula of India, Persia, Arabia Petrsea, the coasts of the 

 Red Sea (especially towards the south), the shores of the Ganges, 

 the Caspian Sea, Upper Egypt, Abyssinia, Nubia (especially in 

 Sennaar, Schendi, Skordofan, Darfu), and Guinea. In America, 

 where it was introduced by Negro slaves, it had already become 

 a native in Curayoa, even in Jacquin's time. Throughout these 

 regions it attacks aborigines and foreigners without distinction of 

 country, or race. 



The disorder frequently becomes an epidemic, according to 

 Pruner, in years of heavy rain, and especially in marshy dis- 

 tricts. It also appears to occur especially at certain seasons of 

 the year. According to Bremser, it is particularly abundant in 

 the East Indies from November to January (the rainy season), 

 and in Upper Egypt, according to Bilharz, shortly after the 

 regular inundations of the Nile. 



The mode of production of the worm in the human body is 

 still enveloped in obscurity. Although the opinions of those who 

 supposed the worm to immigrate by means of bad water (Bernier, 

 Bruce, Niebuhr to Tuschek; the negroes in Schendi, for which 

 reason the water is strained through linen before drinking, or 

 drawn up from a depth of eighteen fathoms in the sea [Arthus], 

 or Gallandat, who says that those who drink no water in Guinea 

 escape), are now being gradually abandoned, and the views of 

 those authors are obsolete, who say that the worm is produced by 

 the use of palm wine, Indian grain, and bread (Kaukiens), of certain 

 fishes or of locusts (confusion with Gordius], or that the eggs and 

 young are brought upon the body by the land wind and evening 

 dew, or by rain and wind, they must nevertheless be referred to on 

 account of their general diffusion. The most convincing proof 

 in opposition to the assertion that the worm is introduced into 

 the body by drinking water, was furnished by a companion of 

 Jacquin, who, when in Cura9oa, did not drink a drop of water, 

 which, as a lover of spirituous liquids, was not very hard upon 

 him. But he was attacked by the worm, whilst Jacquin, who 

 drank much water, remained free from it. A Dutch gencml in 



