261 ANIMAL PARASITES. 



1854-55, and have caused great devastations in many flocks of 

 sheep. 



The gall-ducts are frequently unaltered by these worms ; but 

 are generally considerably dilated, and then often resemble cords 

 of the thickness of the finger. At the same time their walls are 

 remarkably thickened, callous, cartilaginous ; the inner walls of 

 the vessels are dingy, rough, uneven, and beset with bony, cal- 

 careous concretions (phosphate of lime and magnesia), often 

 coloured by bile, which adhere firmly to the walls and even close 

 up the smaller branches. Thtse phenomena extend to the 

 smaller gall-ducts, and these are seen of the thickness of a goose- 

 quill, and often filled with a yellowish, dingy, slimy matter, 

 resembling pus in its external appearance. The secretion of bile 

 in the vessels thus destroyed constantly suffers more and more, 

 nay, it may even cease entirely, or we only find as much bile in 

 the larger ducts as may have been poured into them from the 

 smaller lateral branches uninhabited by Distoma. The bile itself, 

 which is found in the gall-bladder, is altered in its colour ; instead 

 of greenish yellow it has become dingy grayish yellow, and it has 

 an unusual consistence, as it is mixed with a very considerable 

 quantity of mucus. However, it is usually found in tolerably 

 large quantity in the gall-bladder. This last circumstance cer- 

 tainly appears at the first glance to be very contradictory to what 

 has just been said, and also to the fact that the enormous size of 

 the gall-ducts, and the hardness of their walls, has caused 

 death, by mechanical pressure, on a great part of the tissue of the 

 liver and rendered it useless ; but it is easily explained by the 

 circumstance that when the Distoma are present in great numbers, 

 they close up the ductus choledochus almost hermetically, so that 

 the bile behind them and in the gall-bladder is kept back. To 

 sum up the symptoms here described in a few words, we must 

 regard as the first consequences of Distoma in the liver, dilatation 

 and catarrh of the gall- ducts, and destruction by pressure and 

 disappearance of large portions of the parenchyma of the liver in 

 the vicinity of the enlarged gall-ducts. 



Further consequences of these morbid circumstances are, 

 although perhaps rarely and only temporarily, icteric phenomena, 

 which, however, quickly disappear after the removal of the 

 stoppage in the efferent biliary duct. Whether actual symptoms 

 of incarceration, such as we find with tightly wedged gall- 

 stones, may occur in consequence of the passage of the worms 



