PARASITES 439 



dressing is perhaps best confined to those patches which 

 are the most suspicious, to which it should be repeated 

 once or twice. Land on which fluke disease has appeared 

 is not safe to use again for two years, even after drain- 

 age of the soil has taken place* It is important, among 

 other preventive measures, to bear in mind that the rabbit 

 harbours a fluke the eggs of which infest sheep. 



The^ Nematodes contain some very destructive parasites 

 found in the respiratory, circulatory, and digestive apparatus. 

 These nematodes are furnished by the family of Strangles, 

 which are capable in the respiratory or digestive system 

 of producing considerable havoc among cattle, sheep, and 

 horses. 



Broncltial and Pulmonary Parasites. — These are well 

 known epizootic diseases among sheep and calves, pro- 

 ducing what is commonly known as 'Husk' or ' Hoose.' 

 In the case of the above animals great loss of life may 

 occur, but both the pig and horse may also have strongles 

 in the air-passages which are neither widespread nor 

 destructive. 



Authorities do not appear to agree as to the number of 

 different species of strongle found in the bronchial tubes 

 and lungs of cattle and sheep, it is probable that there is 

 one in the ox, and three or four affecting sheep. t 



Strongylus micrurus. — ^The ordinary husk-producing worm 

 of cattle. 



Strongylus filaria. — The husk worm of sheep and lambs. 



Strongylus rufescens — The worm which produces nodules 

 in different parts of the sheep's lung. 



Pseudalius ovis. — Closely allied to S. rufescens and by 

 many considered one stage of its existence. 



S. filaria or the white thread worm, is found only in the 

 bronchial tubes, whereas rufescens, the red thread worm, 



* The views here expressed are those of the late Mr. Finlay Dun, 

 F.E.C.V.S. ; see his valuable paper, ' Report on Liver Eot,' Journal of 

 the Boyal Agricultural Society, vol. xvii., 1881. 



t See papers on the subject by the late Dr. Cobbold, F.E.S., and Sir 

 George Brown, C.B., Journal of the Boyal Agricultural Society, 

 vol. xxii., 1886, and vol. viii., 1897. 



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