558 NODULAR DISEASE IX SHEEP 



nodules may be of various sizes 

 and are found at all times. From 

 these the worm has either es- 

 caped or, in the case of the smaller 

 nodules, the worms have died. 

 The nodules are usually spher- 

 ical, but the cheesy material may 

 appear as a long mass or it may 

 apparently fill what seems to have 

 ^^~ been a worm track. The last ap- 



FiG. 70. Section through ayoung pearance occurs most often in the 

 worm nodule. Worm cavity with small intestines. From the mu- 



worm near the ce?iter. [Curtice). -j x-u j i ^ 



' cous side these nodules present 



little if any color. The older ones may present a greenish-3'el- 



low appearance, especially if the mucous membrane over them 



is thin. In well advanced cases, when the nodules are numerous 



and large, many are found in which the mucous membrane 



over them is ruptured and the cheesy mass protrudes into the 



intestinal cavity. In these no worms have been found and 



hence the conclusion has been reached that they have escaped. 



In lambs the little dots indicating the presence of the 

 young nodules are very .scattering, but m older sheep they 

 ma}' be very nunierous. Between the stage in which a few- 

 are scattered here and there over the cecum and that in which 

 the cecum has become a stiff tube with walls from one-fourth 

 to one-half inch in thickness, there are all varieties. The 

 nodules may extend from the cecum to the anus. They may 

 also be abundant along the small intestine. The cheesy 

 material which the worms produce has been found in the 

 h'mphatics, on the omentum and in the liver, but in these 

 places it never seems to be sufficiently abundant to show that 

 the parasite lived long. 



Microscopic serial sections made from the alcoholic speci- 

 mens show best the changes which have taken place in the 

 surrounding tissue. The worm penetrates to the submucous 

 tissue and irritates it. There is a special cyst for the worm 

 and a thickened adjoining portion of the tumor which is like a 

 surrounding membrane. The adjoining cells rapidly increase 



