XVI. 



NOTES ON THE FLUKE IN SHEEP. 

 By Alfred T. Bkktt, M.D. 



Read at Watford, IQth April, 1880. 



The metamoiiihoses of insects is a subject that has much charm 

 and fascination about it, and the metamorphoses of the Entozoa, or 

 parasitic -worms, are not less remarkable, nor are they less in- 

 teresting than the metamorphoses of insects. It seems that many 

 parasites require to go through the bodies of two animals to acquire 

 their perfect growth. But it is not my intention to detain you 

 with an account of the natural history of parasites in general or of 

 flukes in particular, for the family of flukes is a numerous one, and 

 has been estimated by some naturalists at from 400 to 500 species, 

 all of which are supposed to pass through allied metamoi'phoses. I 

 shall only briefly direct your attention to a few facts connected 

 with fluke in sheep. 



The subject is of great importance. The ' Times ' says, in a 

 leading article, on April 13th, 1880 ; "An insidious and protean 

 creature, called the fluke, is causing losses actually exceeding, in 

 the aggregate, the cost of many of the wars which have figured 

 in the indictment against the Ministry." In 1861 there were 

 3,556,050 sheep in Ireland. Professor Fergusson, in reporting on 

 the disease to the Irish Government, says : " It is my opinion that 

 more than 60 per cent, of the sheep on the island are at present 

 unsound, although not all to a fatal extent." A correspondent in 

 the 'Echo' says: "The losses of sheep in the three counties of 

 Somerset, Devon, and Cornwall may be counted by thousands ; 

 hundreds of farms in these counties are virtually denuded of sheep." 

 I am informed that one farmer in "Watford has lost 400 sheep 

 at Pinner ; and sheep have been sold in Watford Market for from 

 three to four shillings each. 



The fluke is called Distoma hepaticum or Fnsciola Jiepatica. It 

 belongs to the order Trematoda, which denotes that it is a suctorial 

 worm. It is a matter of minor importance whether we speak of 

 this entozoon as a liver-fluke, trematoid worm, Distoma, or Fasciola. 

 Distoma hepaticum varies in size in the same animal according to the 

 age of the entozoon. Although this is the case, it is a singular cir- 

 cumstance, hereafter to be explained, that none are found in long 

 existing cases of rot so small as to warrant the belief that they have 

 been hatched fi'om ova deposited within the biliary ducts. The 

 form is that of an oblong oval, flattened from side to side. It will 

 often attain a length of an inch and a quarter, and a breadth of 

 half an inch in its widest part. It reminds one of a flounder or 

 some flat fish. It will live a few hours after the liver has been 

 removed, and it can be seen to move about. The colour varies 

 according to the amount of bile in the digestive system. If full, 



