PARASITOLOGY. 143 
greenish, cheesy pus has accumulated around it; in 
nodules larger than a pin-head the entire contents 
are a cheesy mass; the cyst wall is ruptured and the 
worm is found free, wandering within the capsule; 
in the larger nodules the cheesy material is quite 
hard except at the side where the worm is found. 
Nearing maturity the worm leaves the nodule and 
becomes sexually mature only in the intestinal tract; 
the nodule now gradually shrinks in size until it is 
quite small and filled with earthy material. 
Animals Intested—The sheep, goat and ox. 
Fig. 53—NoDvuLar DISEASE. 
a, Nodule caused by larva of Oesophagostome of Columbia. 
b, Section of small Intestine. 
Parts Intested.—Small and large intestines. 
Disease Produced.—Nodular disease. 
Condition Produced.—Nodular disease 1s common 
in native but seldom if ever found in range sheep. 
In badly infested cases the entire intestinal canal 
may be thorougly studded with the nodules, which 
are irregular in outline and push the serous coat out; 
the nodule lies under the serous covering of the 
bowel and can be readily told from the tubercle pro- 
duced by the bacillus of tuberculosis by the fact that 
the latter is smooth, and that in tuberculosis the 
lymph glands adjacent to the affected part will be 
