Adults and Ova. 



The morphology of Ibe adult worms, and of the eggs recovered from 



cases of bilharziosis in Egypt, has been dealt with exhaustively by several 



previous writers, notably by Bilharz, Leuckart, Fritsch, Lortet and 



Vailleton, and particularly by Looss. 



In parasites generally there are certain small variations 



Variations, within the limits of a species both in size, shape, etc., of 



adults and of eggs. In Bilharzia hcematohia unusually 



striking and constantly recurring departures from the normal have been 



described. In Looss' monograph on the adult anatomy it is recognized 



that a number of these do actually occur, but others are, in his opinion, 



due to errors in interpretation by previous workers. These abnormalities, 



rather than the normal anatomy, are our more immediate concern. The 



differences that have been recorded in the shape of the eggs are of special 



interest. As early as 1851 Bilharz bad noticed that certain of these, 



passed in the fa?ces, were distorted, the small terminal spine of the typical 



egg being apparently displaced laterally. Those latcral-spined eggs ho 



regarded as abnormalities. 



T^ In 18G4 Ilarley [214] was so struck by the absence of 



Duality . . . . 



T EG • ■ those atypical forms in cases of bilharziosis seen in South 



Africa, that he named the South African parasite Diatomu 



