42 THE LIVEK-FLUKK. 



Trematodes are found in the intestine, biliary canals, bladder, 

 respiratory apparatus, and in the sub-orbital sinus of birds. One 

 of the most important is the Liver-fluke {Distomum hepaticum), 

 which produces the " liver-rot " in sheep or the so-called dido- 

 mrdosis. Another species, also found in the liver region of the 

 sheep, is B. lanceolatum, a smaller and more pointed species. 



The Liver-fluke {D. hepaticum) (fig. 9). — The body of this 

 destructive fluke is leaf-like, flattened, and of an irregular pale- 

 brown colour. It is about an inch in length and half an inch 

 across at the widest part ; it is oval and lanceolate in shape, 

 broader and rounder in front, where it suddenly contracts to 

 form a kind of neck. The cuticle is studded with numerous 

 small prickles, directed backwards, which one can easily feel on 

 pulling the worm through the fingers from tail to head. The 

 oral sucker is terminal, small, and round; 

 the ventral sucker is towards the anterior 

 J^^^^i end, large and round, with a triangular 

 depression. The intestine can be seen 

 ^'^^^3^ I^^M§^ through the integument as two dark 

 forked branches. The ova, which may 

 often be seen in the uterus, are ovoid 

 bodies of a dark-brown colour. 



Lambs are especially affected. The 



Fig. 9— Liveb-fldkf. . . ' 



(tiistumum lupatimm). same speoies is found in goats, cattle, 

 0, Oral sucker ; gp, geiii- camels, the horse, pig, rabbit, and man. 



tal pore; 11, ventral sucker; ' ' i o> > 



ph, piiarynx ; a, alimentary They live chiefly in the biliary ducts of 



canal. "^ ^ ^ "^ 



the liver. Damp wet seasons and damp 

 ground favour the spread of distomatosis. Fields liable to be 

 flooded along the course of rivers are often certain to cause sheep 

 to be infested with Fluke, the cysts being spread over the grass 

 when the floods are out, and afterwards taken in by the lambs. 

 Life-history. — The life-history of this species has been deter- 

 mined by Leuckart and Thomas. The ova pass out from the 

 bile-ducts through the intestine to the ground in the excreta. 

 Each ovum is provided with a lid, vvhich breaks off, and the 



