92 
Parasites of Cattle and Sheep. 
sufficient number of parasites. On this depends the risks of 
over-stocking, and the comparative freedom from the disease 
of sheep having a wide range of pasture. As far as is known, 
these worms reach maturity, or at any rate the stage of egg 
bearing, only in the stomach of ruminants, preferably sheep ; 
and as it is not likely that, in the immature state, the parasite 
would live long apart from the host, it is as well to keep 
sheep off infested pastures as long as possible, after which the 
danger would be averted by the death of the immature worms. 
Curative treatment must be in imitation of that suggested 
for the cattle stomach worm. 
Liver Fluke. — The disease known, as liver rot, coathes, 
iles, &c., caused by the liver fluke ( Distoma hepaticum ), 
has at times during the past forty years appeared as a scourge. 
For several years past our flocks have been remarkably free 
from anything like serious outbreak. It usually follows a 
succession of wet seasons, and in view of a possible recurrence 
of wet seasons during the rainy summer of 1903, the Board 
of Agriculture issued a leaflet of warning and advice as to 
the prevention of this disease, and in the following year 
reprinted, by permission of this Society, the scientific articles 
on this disease which had appeared in the Journal. Happily 
there has been no recurrence of the losses experienced in the 
’sixties and ’seventies. 
From the Board of Trade returns it will be seen that from 
1879 to 1881 there was a diminution of 3,500,000 sheep in 
Great Britain, attributed mainly to liver rot. It is difficult 
to account for the disappearance of the malady. Probably 
certain special climatic conditions, unfavourable to its develop- 
ment, have obtained ; possibly the knowledge of the life- 
history of the fluke has led to the adoption of successful 
measures of prevention. Certain it is that the important 
discoveries of Mr. A. P. Thomas, described in the Journal 
some twenty-five years ago, 1 which completed our knowledge 
of the life-cycle of the parasite, contained the information 
which affords us certain grounds to work on. Though at the 
present time comparatively little interest is likely to be taken 
in the subject, we must not overlook the fact that now and 
again we meet with cases of liver rot, and that flukes are 
not annihilated. Indeed, a few are frequently met with. 
Each individual parasite is capable under favourable circum- 
stances of producing innumerable young flukes. This has 
been variously calculated at from scores to hundreds of 
thousands, so that, should favourable conditions arise, it is 
possible for us to experience a repetition of former troubles, 
1 Journal R.A.S.E., Vol. 42, 1881, p. 1 ; Vol. 43, 1882, p. 439 ; Vol. 44, 1883, p. 276. 
