134 
Tlie Rot in Sheep. 
to the presence of the flukes themselves, and also to their number, 
for an ex})lanation of the fact. 
The ill effects attending' entozoa of every description are 
mostly dependent on the largeness of their number, but not 
unfrequently also on the importance of the organ in which 
they are located. A few flukes, by the simple irritation they 
produce, are frequently non-productive of mischief, at least to 
any practical extent, in deranging the functions of the liver. 
Hence the daily occurrence of sheep, which had been fed for 
the market, and which had gone on to the perfect satisfaction of 
their owner, being found to have a limited number of these 
entozoa in their biliary ducts, the existence of which was not 
only unsuspected, but would perhaps not have been believed 
in, but for the circumstance that they were brought to light by 
the slaughtering of the animal. 
This fact is mainly due to the circumstance that the fluke, as 
has been explained, does not multiply its species within the 
biliary ducts ; for if the contrary were the case — namely, that 
young flukes were produced therein, and that these in due time 
became the parents of otliers — what, it may be asked, would then 
have been the result? Why, that these infected sheep, instead 
of being made fat enough for slaughtering, would gradually have 
lost flesh, and ultimately have died ana>miated, even if not 
more than a dozen of the entozoa had originally occupied their 
biliary ducts. 
Thus we see the necessity of becoming conversant with the 
method of propagation of each entozoon, to be enabled to speak 
with any certainty of the ill effects attending its presence. The 
trite remark, " Oh, a few worms do no harm," may prove true, 
provided the parasites are inhabiting a part of the organism 
which is comparatively of little importance to the direct main- 
tenance of vitality, and that they do not multiply their species 
therein so as greatly to increase in number and speedily lay the 
foundation for structural disease. 
Much also of the ultimate mischief resulting from entozoa will 
depend, as has been stated, on the importance of the organ in 
which they may be situated. Thus a sinr/le hydatid in the brain 
will by its pressure produce serious disease, and ultimate death 
of the affected animal ; while a dozen or more hydatids located 
within the lungs, liver, or other organs, will be unrecognised 
during life from any pressure or irritation they may produce. 
Facts of this description are frequently too little regarded 
in estimating the influence of parasites on the health of animals. 
They have, however, an important practical bearing on the dis- 
ease in question, as has been already explained. 
