260 



THE ANIMAL PARASITES OF MAN 



Vitellarium 



Ovary 



Testis 



Distribution. This species occurs very frequently in man, in 

 certain districts of Japan, especially in the province of Okayama, 

 Central Japan, in particular localities of which above 60 per cent, of 

 the population are infected. The worms are sometimes found in 

 enormous numbers in the liver (upwards of 4,000), also in the 



pancreas and rarely in the duo- 

 denum. It is common in Tonkin 

 and Indo-China. Leger in Tonkin 

 found 50 per cent, of people ap- 

 parently in normal health infected, 

 so that probably symptoms only 

 arise when the infection is intense. 

 [The exact distribution of these two 

 species is, however, not precisely 

 defined at present, as commonly no 

 distinction is made between them. 

 J. W. W. S.] 



Verdun and Bruyant deny, in 

 opposition to Looss, the possibility 

 of being able to distinguish within 

 the genus Clonorchis the two species 

 described, but they admit the justi- 

 fication for the new genus. They 

 also report the occurrence of Opis- 

 thorchis felinens in man in Tonkin 

 (Compt. Rend. Soc. de BioL t Ixii, 1907). 

 Pathology. Both species of Clon- 

 orchis give rise to grave symptoms. The liver is generally enlarged, 

 though when the infection has lasted some time it begins to contract. 

 The surface of the organ is studded with white vesicles, and on cutting 

 into it one sees numer- 

 ous cavities with thick- 

 ened walls (distended 

 bile-ducts) filled with a 

 brownish fluid contain- 

 ing innumerable eggs, 

 which cause its colour. 

 Microscopically, the epi- 

 thelium of the bile-ducts 

 is either (i) entirely de- 

 stroyed, or (2) actively 

 proliferates, forming an adenomatous outgrowth. Occasionally this 

 proliferation is not limited by the wall of the bile-duct but pene- 

 trates it and leads to a growth of numerous new ducts, forming a 



Seminal 

 receptacle 



Excretor) 

 vesicle 



- Testis 



FIG. 160. Clonorchis endemicus. 

 about. (After Looss.) 



FIG. 161. Clonorchis endemicus : eggs. The knobs 

 on the eggs are not shown, x 900. (After Looss.) 



