off with the body excretions. They may live for a short time outside the
animal body, or undergo certain development and again infest a host of the
same species from which they came, through the water, grass and fodder that
the animal may take into its digestive tract.

[Illustration: FIG. 75.--Large round-worm in intestine of hog.]

The following species of nematoids are common parasites of domestic
animals:

SOLIPEDS

Species Organ
Ascaris megalocephala Intestines
Sclerostoma equinum Large intestine and blood-vessels
Sclerostoma tetracanthum Large intestine
Oxyrus curvula Large intestine
Oxyrus mastigodes Large intestine

CATTLE

Species Organ
Strongylus convolutus Abomasum
Ascaris vituli Small intestine (calves)
Strongylus ventricosus Small intestine
Oesophagostomum inflatum Large intestine
Trichocephalus affins Large intestine
Strongylus micrurus Bronchi
Strongylus pulmonaris Bronchi