STOMACH WORMS IN LAMBS AND THEIR CONTROL                 269

directed with a view to checking the disease should be carried out against this
parasite.

                                                TABLE I.

Showing the number and species of helminths found in the intestinal tract of 2 lambs
                                suffering from parasitic gastritis.

The fact that in Scotland H. contortus occurs in sheep in relatively small num-
bers compared with O. circumcincta is not without interest. Generally speaking in
U. S. A. and South Africa the reverse is the case, H. contortus being more important
from an economic point of view than O. circumcincta, although according to a recent
report on parasitic diseases in U. S. A. (1932) the lesser stomach worm is stated to
be more common in some parts than others, particularly on the West Coast. A
similar state of affairs exists in Australia, for according to Seddon and Ross (1929),
H. contortus is of the greatest importance as the cause of parasitic gastritis in New
South Wales and Queensland, but to a less extent in the Southern Australian States
where infestation with O. circumcincta appears to be more common.

The literature on the control of stomach worms by the administration of
anthelmintics is extensive and it is well known that H. contortus can be readily
controlled by dosing with copper sulphate. Unfortunately O. circumcincta is much
less susceptible to the action of anthelmintics and no drug which will remove this
parasite effectively from the abomasum has as yet been discovered.

Control of stomach worms by a system of folding pastures has long been advo-
cated, and some of the results obtained by this method for H. contortus have been