146 



VETERINARY STUDIES 



intestine; i.e., the nodules. The contents of these nodules is 

 usually cheesy, and greenish or yellowish in color. 



Later the young worms leave the nodules and mature in the 

 intestinal canal. 



Some of the eggs and adult worms pass out with the manure, 

 and thus infect the pastures and feed yards, ponds, or sluggish 

 streams which receive their drainage. 



Fig. 50. — Nodule Disease. (M. H. B.) 

 Intestines of sheep. 



Injury done. — The extent of injury to the individual sheep 

 depends mainly upon the number of worms present, and the con- 

 dition of the sheep as to vitality and resisting power. There 

 may be something of an inflammation of the bowels while the 

 young worms are passing through the lining of the intestine, 

 but the main injury is that of starvation. So large a portion of 

 the bowel is affected by the parasites when they are present in 

 great number that there is not enough healthy tissue for ab- 

 sorption of food material. It may be, also, that the worms ex- 

 crete poisonous substances; or their presence may lead indi- 

 rectly to the formation of poisonous materials which are ab- 

 sorbed. A badly infested sheep may have plenty of good food 



