216 BRITISH SHEEP AND SHEPHERDING. 



a thick layer of tenacious mucus to form, and this provides an almost 

 perfect protection for them. If success is ultimately attained, it 

 will probably be by some alkaline washing of the stomach and 

 thinning down of the mucus before sending in such doses of tobacco 

 as the patient can bear, if sustained by stimulants. Arsenical 

 tablets and turpentine in linseed oil have some little effect in 

 checking the increase of the worms ; and the administration of salt, 

 iron and Peruvian bark helps to sustain the strength of the animals 

 while awaiting the time of their departure. In the matter of pre- 

 ventive treatment, we may take a hint from the discovery of the 

 Grouse Commission in the case of another worm of the same 

 family, the S. pergracilis. This parasite passes ova from the in- 

 fested bird which develop into motile embryos capable of reaching 

 the tips of the heather in four or five days, from which they are 

 taken by the birds. There is therefore a period of migration, when 

 salting and rolling the land must be the means of destroying 

 myriads of strongles of the kind which infest sheep. (See Husk 

 or Verminous Bronchitis.) 



SCOURING CAUSED BY WORMS. 



Scouring or diarrhoea has been several times referred to in other 

 sections of this work, and among the causes strongylosis or infesta- 

 tion by minute thread-like worms mentioned. Another and most 

 serious cause of scour is 



TAPEWORM. 



There are many tapeworms recognised by the helminthologist, 

 but the commonest offender is the Taenia expansa, and it often 

 attains to a great length, while vast numbers afflict a single animal. 

 Lambs are preferred as hosts, but adults do not escape. All tape- 

 worms pass through three stages, the egg, the hydatid or cyst, and 

 the mature worm. A variety of intermediate hosts are known. 

 Soft molluscs are among them. Where many rabbits are found, 

 tapeworm is gene ally present among the flocks ; where dogs overrun 

 pastures, gid is prevalent (see Gid, sturdy or turnsick). For the 

 full history of the tapeworm the reader will consult such works 

 as Pneumann's " Parasites and Parasitic Diseases." We are more 

 concerned here with the methods of prevention and of treatment 

 at present practicable. 



Symptoms. A previously healthy flock begins to scour and to 

 do badly. Other causes do not appear. The dung should, as 

 advised elsewhere, always be examined, and not only when disease 

 appears, but as a matter of habit. Small segments of tapeworm 

 or proglottides as they are called, will surely be found if carefully 

 looked for. On some days it may be necessary to make quite a 



