ANCYLO STOMA 



667 



that it was the cause of Egyptian anaemia. Wucherer, in 1872, 

 found that it was the cause of tropical ansemia in Brazil (called 

 ' oppilagao ' ). Perroncito found that it was the cause of the ansemia 

 which badly affected the miners employed in the St. Gothard tunnel. 

 Grassi and Parona in 1878 discovered the eggs in the faeces, thus 

 enabling a diagnosis to be made during life. The wide geographical 

 distribution of the parasite, and the amount of disease which it 

 causes, is slowly being realized, and the deaths from anaenaia, 

 general dropsy, and so-called beri-beri, etc., in different tropical 

 regions are being found to be due to this animal. 



The development and method of infection have been completely 

 traced out by Looss in Egypt in a most masterly manner. 



Fig. 290. — Copulation of Ancylostoma. 

 (From a photograph by J. J. Bell.) 



In 1902 Stiles found that under the term Ancylostoma two dif- 

 ferent parasites were being confused, one corresponding to Dubini's 

 Ancylostoma duodenale, and the other new, which he named 

 Necator americanus. Leiper has shown how widespread this latter 

 parasite is in the Old World. 



The geographical distribution is probably not fully known, 

 because in many places it is confounded with Necator. It is sup- 

 posed to be cosmopolitan in tropical regions, and in mines and 

 tunnels in colder climates, in which, of course, the air-temperature 

 is higher than that of the outside. 



Morphology. — The body is cylindrical, tapering from back to 

 front in both sexes. During life it is flesh-coloured. The cuticle 

 is ringed. The mouth is terminal, with a chitinous wall, which 

 ventrally carries two pairs of hook-like teeth, and dorsally one pair. 

 Close to the base of the outer ventral tooth opens the single-celled 



