UNIVERSITY OF CALIFORNIA PUBLICATIONS 



ZOOLOGY 



Vol. 18, No. 17, pp. 485-507, 3 figures in text 



January 4, 1919 



THE CERCARIA OF THE JAPANESE BLOOD 



FLUKE, SCHISTOSOMA JAPONICUM 



KATSURADA 



BY 

 WILLIAM W. CORT 



CONTENTS 



PAGE 



Historical 485 



Material 489 



Method of study 490 



Characters of the schistosome cercariae 491 



Structure of the cercaria 492 



Oral sucker and cephalic glands 496 



Activity of the cercaria 502 



Literature cited 504 



HISTORICAL 



The discovery of the intermediate stages and methods of entrance 

 into man of the human blood flnkes is of very recent date. Guided by 

 the knowledge of the life cycles of related forms, numerous workers 

 attempted without success to find intermediate hosts for these species. 

 After repeated efforts to find the larval stages of the Egyptian blood 

 fluke. Schistosoma liaematohmm, in Egyptian molluscs, Looss finally 

 advanced the hypothesis that no intermediate host was needed in the 

 life cycle of this species and that man Avas infected by the miracidium 

 penetrating through the skin. According to this hypothesis, the inter- 

 mediate stages developed in the liver of man. Looss supported his 

 contention in a number of articles (1894, 1905, 1908, 1909), but with- 

 out adducing any positive experimental evidence. In fact, numerous 

 attempts to infect experimental animals directly with the miracidia 

 of the human schistosomes were entirely without success (Looss, 1905 ; 



