XLYI. 

 ENTOZOA OF THE SHEEP. 



Sheep are infested with four varieties of tapeworms. A tape- 

 worm consists of a head and several joints, or suckers. The suck- 

 ers and hooks hold on to the mucous memhrane of the intestines. 

 They multiply by the lengthening of the neck. The head has 

 four suckers. They have no generative organs, no mouth, nor 

 digestive organs, but live by absorption of nourishment through 

 pores. Each segiuent may come off from the rest. 



TAENIA COENURUS. 



This parasite infests the intestines of the dog, from which per- 

 fect segments are expelled. These segments falling in the pas- 

 ture where sheep are feeding, are swallowed with the herbage; 

 getting into the blood vessels, they are carried to every part of 

 the body, and are lodged in the brain. Here the young embryo 

 covers itself. It is then the size of a mustard seed, and gradually 

 grows. This parasite causes the disease in sheep known as sturdy 

 tumsick or gid. The parasite encysts itself in the brain, the cyst 

 measuring in diameter one-half inch to a hen's egg. Usually but 

 one cyst is found. They generally attack lambs under one year 

 old; sheep above two years old being rarely affected. The ail- 

 ment prevails largely in flocks where dogs are employed to assist 

 the shepherds. On enclosed pastures, w^here the sheep are un- 

 attended by dogs, the disease seldom occurs. 



Symptoms. — The animal becomes dull and stupid. If miade to 

 go on, he may dash into the wall or fence, turning to the right or 

 left, as controlled by the hemisphere of the brain in wKich the 

 parasite is located. When the parasite is lodged between the 

 hemispheres, the animal steps high and goes fonvard in a straight 

 line; the head is carried upwards, and there may he a rorying 

 81 ( 481 ) 



