588 



TREMATODA 



1903 Manson observed the same fact in a patient from the West 

 Indies. In 1907 Sambon created a new species, Schistosoma 

 mansoni, for the following reasons : — ■ 



1. Lateral-spined eggs are never found in the urine, but only in 

 the faeces, and never occur in the bladder, only in the rectum 

 and liver. 



2. The egg is oval in shape, with a lateral spine, while that of 

 5. hcematobium is oblong and lanceolar in shape, with a 

 terminal spine, and that of S. japonicunt oval or roundish, 

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

 examined by Looss. 



The lengths and breadths are different : S. mansoni, 112 to 162 [ju by 

 60 to 70 iji) S. hcematohium, 110 to 120 ^ by 46 to 50 pt,', 

 S. japonicum, 75 to 90 ju by 53 to 75 jbi. 



3. The males are apparently similar, but the females have a differ- 

 ence in the genital tract, which has been described by 

 Fritsch, and when mature contain lateral-spined ova in the 

 uterus. 



4. The geographical distribution of S. mansoni and 5. hcematohium 

 is difterent. 5. hcematohium is alone found in the Cape; 

 5. mansoni is the only species in the West Indies and in South 

 America. 



Looss in Egypt immediately challenged Sambon's statements, but 

 the history of this polemic will be found in the earlier editions of this 

 book. We have all through felt that Bilharz, Sonsino, Manson, 

 and Sambon, were right, and Ward always supported Sambon, and 

 now this has been proved experimentally by Leiper to be correct. 



In 1909 Da Silva described the adult worms as follows: — • 



Males.— The male measures 12 millimetres in length by 0*448 millimetre 

 in breadth in the middle. The ventral sucker is 0-540 millimetre behind 

 the oral sucker. 



The anterior end shows six sexual masses composed of testes and seminal 

 vesicles. The posterior end is tapering. The spinous papillae are not 

 so marked as in 5. hcsmatobium. 



Females. — The female worms measure 14-5 to 15 millimetres in length by • 

 0'i68 millimetre in breadth in the middle. The distance between the 

 two suckers is 0-224 "to 0-252 millimetre. It is thickest in the middle, 

 and tapers to each extremity. The anus opens 0-336 millimetre in 

 front of the tip of the tail. The oviduct is much shorter than in 

 S. hcsmatobium, and enters the vitelline ducts after only a short turn. 

 The uterus contains laterally spined eggs. The eggs measure 146 by 

 62 jii, with 18 /i, as the length of the spiculum. The miracidium escapes 

 by a transverse rupture of the shell, and measures 153 by 72 /x. 



In igii Flu, in studying the Bilharziosis in Surinam, concluded that 5. 

 mansoni is distinct from 5. hcematohium because: (i) 5". hcsmatobium has eggs 

 differently shaped from those of 5. mansoni ; (2) the anterior border of the 

 lateral folds in the male S. hcsmatobium forms almost a right angle with the 

 anterior portion of the body, while in S. mansoni the transition is more 

 gradual; (3) the ovaries of 5. mansoni have always a more or less winding 

 course, a character not described for any other species of Schistosoma ; (4) the 

 ootype is asymmetrical in relation to the long axis of the worm; the oviduct 

 opens laterally on the ventral side where the shell gland is situate; (5) 5. 

 mansoni lives in the region of the mesenteric veins, and S. hcsmatobium pre- 



