202 



DISEASES DUE TO INTERNAL PAIiASITES. 



tributed on the ground or in the drinking water by other animals, 

 such as wolves, foxes, coyotes, etc., but more especially is the dog 

 responsible for sowing the germs of this disease. The prevalence 

 of this disorder depends to a great extent on the use of sheep 

 dogs, it being noticeable that where the sheep run in enclosed 

 pastures where dogs are not required to assist the herders, the 

 liability to infection is reduced to a minimum. 



The eggs of the tapeworm on being swallowed by the sheep 

 hatch within its stomach, immediately pierce the walls of that 

 organ and gain entrance to the circulation. They are then car- 



OXiXCdoZD; 



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'M:>n;xxX3::i 



'Caenia Coenurus. Hdutt, JVatwrat Size. 



(Raillet.) 



ried to the. different parts of the body, those which reach the 

 brain and spinal cord remaining in those organs, developing into 

 cystic bodies, which continue to thrive and grow at the expense 

 of the tissues. The others which fail to reach the brain and 

 spinal cord may locate temporarily in the heart, lungs, 

 diaphragm, etc., where they seem to grow for a time and then 

 disappear. On reaching the brain substance the young para- 

 sites pierce the tissue, lodging in it and commence to develop. 



