II. TREMATODA: DISTONE^I. 



277 



kin-seed. It lives in the bile-ducts of sheep, cows, pigs, etc., and rarely 

 (twenty known cases) of man. It stops up the ducts and causes a disease 



DEVELOPMENT OF DISTOME^E. 

 (a) Simple (ft) Ordinary (c) Complicated 



* 



known as 'liver rot,' generally resulting in death. The history as 

 described above shows why sheep pastured in moist places are subject to 

 tho disease, and why wet seasons are times of epidemics. Thus in the 

 rainy year of 1830 about one and a half mil- 

 lions of sheep were killed in England ; in 

 1812, 300,000 in the neighborhood of Aries, 

 France. This species is frequently accom- 

 panied by D. lanceolatum, less than half an 

 inch in length (fig. 233). 



Bilharziahcematobia is a human parasite, 

 most common in hot climates, and especially 

 so among the Fellahin of Egypt. The sexes 

 are separate. The male, half an inch long, by 

 inrolling of the ventral side (fig. 237) forms 

 an incomplete canal (canalis gynsecophorus) 

 in which the more slender female usually lies. 

 These united worms occur in the portal vein 

 and connected vessels. They follow these 

 vessels in either direction and lay their eggs 

 in the mucous membrane of the ureters and 

 urinary bladder, as well as in liver and intes- 

 tine. The suppurative sores of the urinary 

 tract cause albuminuria or, by hemor- 

 hage, haematuria. Diagnostic of the dis- 

 ease is the presence of the eggs, each with a 

 spine, in the urine. Several other species 

 occur in man, among them D. carnosum* and Z>. westermanni* in 



Fio. 237. Bilharzia hcematobia. 

 Female in the gynaecophoral 

 canal (c) of the male; s', s", 

 anterior and posterior suckers. 



