CHAPTER XIV. 



parasitic Diseases, Due to Internal Parasites. 



Parasites are living animal-organisms, which extract nour- 

 ishment for their existence from the tissues of their host. Of 

 these we shall recognize two general classes. 



Entozoa, those which live on the natural cavities or solid 

 tissues of the animal. 



And Ectozoa, those infesting the outer surface, or skin, 

 existing on the effusion created by the irritation caused by their 

 presence. 



In this chapter we shall consider only the diseases due to the 

 presence of the entozoa, or internal parasites. In sheep we find 

 that parasites are the cause of many of the most serious diseases 

 — they invade all the organs of the body, from the brain to the 

 recturii, their multiplication and resultant damage being in 

 direct -proportion to the neglect and bad management on the 

 part of the flock OAvner. 



parasitic Disease of the Brain. 



Sturdy, 6tcl, Curnaich. 



This is a condition due to the presence of a larval tapeworm 

 or hydatid in the brain substance, the parasite as seen in its cystic 

 state imbedded in the brain being termed the coenurus cerebralis. 

 It is caused from the ingestion by the sheep of the eggs of the 

 taenia coenurus — a species of tapeworm, which have been dis- 



