CONDITION OF THE LIVER IN SCHISTOSOMIASIS. 227 



presence on the arterial side. Now let us conjecture that the female, 

 leaving the male in the larger arteriole, migrates into a small vessel which 

 she will just occlude. Attaching herself as in the case of Bilharzia, she 

 deposits her ova, not into a venous radicle, but into the distal side of 

 the arteriole where the ova will be aspirated onward, the more so as in 

 this case they are not provided with spines. Finally they reach the 

 intervening capillaries which have a caliber of perhaps 12 to 20 /x, while 

 the ova which must pass, measure, on the average, 40 p.. If the pressure 

 on the mass of ova is sufficiently great to force a portion of their num- 

 bers through the vessel wall, it is not unlikely that another part will be 

 forced through a distended capillary, especially as under the latter cir- 

 cumstances they would be compelled to pass through a distance of no 

 more than 0.5 millimeter before larger venous radicles would be reached, 

 this distance being the average length of a capillary. Having success- 

 fully passed the capillaries, nothing would intervene until the liver was 

 reached, where all but the exceptional ovum would lodge. The fact- 

 that these exceptions exist, as is proved by the occasional ovum found in 

 the lungs, kidneys and elsewhere, strengthens the evidence of their pass- 

 ing through the capillaries of the pelvis. The marked difference in the 

 pathology of the two diseases, bilharziosis and schistosomiasis, may there- 

 fore depiend first, on the location of the parasites : the one in the venous 

 and the other in the arterial side of the portal circulation; and, second, 

 on the morphological difference in the ova. 4 



V. GEOGRAPHICAL LOCATION. 



There is nothing in the history of the case we report that is of any 

 assistance toward clearing up the mystery of the mode of infection, 

 nor, on the other hand, anything inconsistent with the theory put 

 forward by the Japanese physicians that the infection is acquired by 

 contact with stagnant water containing the embryos of the parasite. 

 Prom the relatively small number of ova present it is fair to infer 

 that the infection we studied was of a comparatively recent origin, and 

 that it was acquired after the patient joined the military service. The 

 Scout companies in the Visayas have performed much active duty in the 

 field during the past few years and probably have frequently found it 

 necessary to wade stagnant pools similar to those described by Katsurada 

 as being the habitat of the embryo of this parasite. 



4 Professor Akira Fujinami has recently published an article on Schisto- 

 aomum japonicum in which he states that the usual habitat of the adult 

 parasite is in the portal system, it having been found by him in the intestinal 

 veins, the mesenteric veins, the branches of the portal vein within the liver, and 

 in the splenic vein. It therefore appears as if the morphology of the ova, rather 

 than the location of the adult parasite, is the chief factor in the distribution of 

 the ova in the tissues of the body. 



