218 THE FLUIvES 



of Schistosoma hcematohium except that infected faeces instead of 

 urine contaminates water inhabited by a suitable intermediate 

 host, as Planorbis boissyi. 



A third species of Schistosoma, S. japonicum, is endemic in 

 parts of Japan, China and the Phihppine Islands, and perhaps 

 in many other oriental countries. It is slightly smaller than 

 the other species (about two-fifths of an inch in length) and pro- 

 duces eggs (Fig. 6oC) which do not have the spine that is so 

 characteristic of the other species of Schistosoma, but only a 

 rudiment in the form of a little lateral knob. The eggs of S. 

 japonicum, like those of S. mansoni, are voided from the intestine 

 with the faeces. They also frequently become lodged in the 

 liver gall bladder, walls of mesenteric bloodvessels, spleen, pan- 

 creas, and sometimes other organs, not even the brain being 

 exempt. The female worm must in some way deposit her eggs 

 outside the bloodvessel in which she lives since they are ap- 

 parently carried to their destination by the lymph streams. 

 Severe infections with this parasite usually prove fatal sooner or 

 later, and post-mortem examinations show many of the organs 

 of the body to be badly affected. Infection with S. japonicum 

 is associated with a skin disease known to the natives as " ka- 

 bure," and probably caused by the burrowing of the cercariae 

 in the skin. According to Laning of the U. S. Navy, it is not an 

 uncommon thing for large per cents of the crews of patrol gun- 

 boats in the Yangtze River to be completel}^ disabled by infection 

 with this parasite. Laning divides the disease caused by *S. 

 japonicum into three stages. The first stage, lasting from three 

 to six weeks, is marked by high afternoon temperatures, slow 

 pulse, respiratory troubles, transient oedema and rash on the 

 skin and mucous membranes, abdominal pains, digestive irregu- 

 larities and sometimes mental disturbances. The second stage 

 is marked by enlarged liver and spleen, dysenteric symptoms, 

 anemia and irregular fever. The third stage, which does not 

 always occur, but may appear in from three to five years where 

 there are constant reinfections, is marked by diseased liver, 

 oedema of legs and arms, emaciation, anemia and dysentery, 

 and death from exhaustion is not uncommon. 



The life history and mode of infection in the case of S. japonicum 

 is undoubtedly very similar to that in other species of Schistosoma. 

 Miyairi, a Japanese investigator, found reproductive stages of 



