INTESTINAL SCHISTOSOMIASIS 255 



In 1907 Sambon formed a new species of it and called it S. mansoni. 

 His reasons were that : — 



(i) Lateral-spined eggs are never found in the urine or bladder, 

 but only in the faeces, rectum and liver. 



(2) The egg is oval with a lateral spine; that of S. haematobium is 



more oblong with a terminal spine; and S. japonicum is more 

 rounded with a very small lateral spine in 75 per cent, of those 

 examined (or, as some declare, with no spine at all). 



The average size of the S. mansoni egg is 150 by 65 fi with 

 a straight terminal spine. 



The average size of the S. haematobium egg is 115 by 58 /^ 

 with a thick lateral spine. 



The average size of the S. japonicum egg is 82 by 68 /^ 

 without a spine. 



(3) The females differ in the genital tract, and the uterus contains 



lateral-spined ova. 



(4) The geographical distribution is different. 



S. haematobium only is found at the Cape. 



S. mansoni only is found in the West Indies and S. America. 



THE THEORY OF LOOS. 



Loos disagrees with the above saying that the lateral-spined eggs 

 are the products of unfertilized females. The females not being 

 embraced by the male cannot withstand the blood-stream and become 

 carried into side channels, finding their way into the bowel. These 

 unfertilized females only shed laterally-spined ova which are passed 

 in the fasces. 



Again he says that lateral-spined ova are frequently found in the 

 fceces. He declares that there are no differences between the female 

 generative organs. 



The straight-spined ova have been found in the urine in the West 

 Indies. 



As man is probably the intermediate host, there can be no limit to 

 the S. haematobium. 



In 191 1 Looss modified his view, and stated that the eggs develop 

 pathogenically. 



There are many supporters of Sambon's theory. 



It is agreed that lateral-spined ova cause : — 



INTESTINAL SCHISTOSOMIASIS. 



DISTRIBUTION. 



It is found in Egypt, Central Africa, Uganda, South Africa, 

 Belgian Congo, America, and the West Indies. 



