MOLLUSCAN INTERMEDIATE HOSTS OF THE ASIATIC 



BLOOD FLUKE, SCHISTOSOMA JAPONICUM, 



AND SPECIES CONFUSED WITH THEM 



By PAUL BARTSCH 

 Curator of Mollitsks and Cenozoic Invertebrates, U. S. National Museum 



(With Eight Plates) 

 INTRODUCTION 



The importance which certain groups of insignificant-looking, small 

 inollusks possess, because they have been proved to serve as inter- 

 mediate hosts in part of the life history of parasites that in their 

 adult stage affect man or his domestic animals, is demonstrated by 

 the number of pages that have been devoted to them in the medical, 

 scientific, and popular press. 



Prior to the discovery of the Japanese blood fiuke of man, Schisto- 

 soma japonicuui Katsurada. by Miyairi and Suzuki in 191 3. and the 

 working out of its life history in japan, little attention was paid to 

 the mollusks serving as intermediate hosts for that dire disease- 

 producing organism. In fact, the species involved in the Japanese 

 Empire were unknown to science at the time. 



The brilliant researches by Japanese investigators were the first to 

 make known definitely that an intermediate host problem existed in 

 schistosomiasis. These and other studies demonstrated that an in- 

 conspicuous amphibious mollusk shared with man. the dog, cat, cattle, 

 and rat, an ailment that may affect, as recorded by b'aust (48, p. 432), 

 a hundred million inhabitants of China, as well as many in Jajian 

 and a lesser number in Formosa and the Philippines. 



The molluscan material from the Asiatic continent and ofif-lying 

 islands, particularly the inconspicuous fresh-water animals, had up 

 to this time received scant attenticMi. They had little to commend 

 lliem to humanity at large, and the number of molluscan students 

 collecting them were few and their endeavors restricted to limited 

 localities. It is therefore not surprising that our knowledge of them 

 was as fragmentary as it proved to be at the time that schistosomiasis in 

 Japan came to the fore. Even now, as this paper will show, the subject 

 is not exhausted, but enough information is at banc! to point a way 

 for future exjjloration in the molluscnn field and to sliow its medical 

 importance. 



Smithsonian Miscellaneous Collections, Vol. 95, No. 5 



