322 DISEASES OF SHEEP. 



motions, and is becoming rapidly blind. Death generally 

 ensues from starvation. 



Veterinary writers and agriculturists have differed very 

 materially as to the cause of hydatid, some attributing it 

 to certain poisonous plants — but these have never been 

 pointed out ; others considering it a species of serous apo- 

 plexy, and others still contending that it arises from local 

 weakness of the brain, etc., etc. Autopsical examinations 

 have, however, proved it to arise from a different cause, 

 viz. : Coenurias cerebralis, or hydatid in the brain, found 

 floating in a serous fluid, contained within a sac or bladder, 

 thus constituting Sturdy, Gid, Turnsick, etc. It attacks 

 sheep from the sixth to the eighteenth month. 



* Certainly the most common cause consists in the lamb 

 or young sheep picking from the pastures the ova or larvae 

 of the icenia solium, which infests the shepherd's dog. If 

 Echinococcus, polymorphus or vetrinorium, be swallowed 

 by the dog, they are developed into tape-worm, with but 

 few serrations. The minute ova are gathered and swal- 

 lowed with the food of the sheep or lamb, and are taken 

 up from the surface of the intestines. They find their way 

 into the blood, and finding a convenient nidus among the 

 loose textures of the brain, are there deposited. Nature 

 sets to work and encloses these foreign bodies in a mem- 

 branous sac, so that otherwise they may not produce fatal 

 consequences, and in the short period of three months they 

 are found to have reached the size of a filbert. 



Conversely, if these hytatids are swallowed by the dog, 

 they are developed into tape-worms. Hydatids may be 

 prevented in sheep by curing or preventing tape-worms in 

 other animals, especially the dog. As before mentioned, 

 hydatids only affect young sheep, and spring from the ova 



*Findlay Dun. 



