SCHISTOSOMA HAEMATOBIUM 



585 



1864 in a patient from the Cape of Good Hope. Since then it has 

 been found widely distributed through Africa (Egypt, Sudan, Tunis, 

 Algiers, West Coast, including the Gold Coast, East Coast, and 

 South and Central Africa), which is its endemic centre, and in Asia, 

 in .Syria, Arabia, Mauritius, Persia, India. Only imported cases 

 occur in Ceylon. 



Other species are known in sheep, horses, oxen, etc. 



In 191 5 Leiper discovered its complete life-history in the snail 

 and its method of entry into the vertebrate. 



i3 



Fig. 226.- — Schistosoma hceynatobium. 



(After Looss, from Mense's ' Tropen- 

 krankheiten.') 



This drawing shows the female 

 worm enclosed in the gynaecophoric 

 canal of the male. 



Morphology — Male. — The male is 

 whitish in colour, and from 12 to 

 14 millimetres in length, with a 

 greatest width behind the ventral 

 sucker of i millimetre. It is really- 

 thin and flat, though it may look 

 cylindrical, because the lateral 

 margins are turned ventrally inwards, 

 enclosing a canal, called the ' gynae- 

 cophoric canal,' in which the female 

 lies. The whole body is covered 



Fig. 227. — Egg of Schistosoma 

 hcsmatobium (X250). 



(After Looss, from Mense's 

 ' Tropenkrankheiten.') 



with projections tipped with short spines, which enable it to cling to the wall 

 of the bloodvessel. The oral sucker looks ventrally. The ventral sucker is 

 situate near to it. There is -no pharynx, but the oesophagus is long and 

 covered with numerous glands, and bifurcates just in front of the ventral 

 sucker into the intestinal caeca, which unite behind the testes into a median 

 trunk. The excretory pore is at the posterior end, situated a little dorsally. 

 There are four to five testes, from which the vas deferens runs to a vesicula 

 seminalis, from which an ejaculatory duct proceeds to the genital pore, 

 situated behind the ventral sucker at the beginning of the gynaecophoric 

 canal. 



Female. — The female worm is long, thin, being 20 millimetres in length 

 {i.e., longer than the male) and 0'25 millimetre in breadth (much thinner 

 than the male) . Posteriorly it is coloured dark brown, because of the colour 

 of the contents of the intestine. The cuticle is smooth, except in the sucker 

 and at the tail end, where there are large spines. The alimentary canal is 

 much the same as in the male. The ovary is median, and the ovarian duct, 



