orms which burrow
in the intestinal wall during a certain stage in their life history,
sometimes apparently produces serious effects, particularly in young
cattle, but commonly has little or no perceptible influence on the general
health. It, however, often renders the intestine unfit for use as sausage
casings, and as it is widely prevalent among cattle the loss from this
source is considerable. The greenish or yellowish nodules with cheesy
contents are frequently mistaken by the inexperienced for lesions of
tuberculosis.

The life histories of the various small roundworms occurring in the
intestines of cattle, so far as they have been worked out, are very similar
to that of the twisted stomach worm as described on page 519.

_Treatment for intestinal roundworms._--The preventive measures are similar
to those recommended in the case of the twisted stomach worm (p. 521).
Medical treatment is generally not very satisfactory. According to the
Oklahoma Experiment Station, the addition of 1 per cent of tobacco to the
bluestone solution used in the treatment of stomach worms in sheep is
effective in the removal of hookworms. The bluestone and tobacco mixture
described on page 524 may be of value in the treatment of hookworms in
cattle. It is asserted by one author that 2 or 3 drams of rectified
empyreumatic oil in a mucilaginous emulsion, followed the next morning with
a purgative of 1 to 1-1/2 pounds of sulphate of soda, will expel the large
roundworms (_Ascaris vitulorum_).

PROTOZOA.

A number of species of protozoa have been reported as parasites of the
intestines of cattle. To one species has been attributed a serious disease
of cattle in Switzerland known as red dysentery, but so far comparatively
few cases of this disease have been recorded in America. It is probably
more common than is generally supposed. Calves particularly seem most
likely to be affected.

FLUKES IN LIVER AND LUNGS.

Two species of flukes occurring in the liver and lungs are known to affect
cattle in the United States. These parasites are flat, leaf-like worms;
one of them, the common liver fluke (_Fasciola hepatica_, fig. 19), is less
than an inch in length, while the other, the large American fluke
(_Fasciola magna_, fig. 20), is considerably larger when full grown. In
their life history these flukes depend on snails as intermediate hosts. At
a certain stage of development the young flukes leave the snails, become
encysted on stalks of