ADDRESS. 
7 
mals. They may be only a source of debility or inconvenience, but 
they are sometimes destructive and fatal to an excessive degree- 
There are not many of them, I believe, that infest the horse, and 
but few that do much damage to the ox ; but in the sheep they are 
sometimes abundant and dangerous, and the pig, as you know, is 
their favorite stamping-ground. They are microscopic in size, 
and often difficult to detect, because they enter the body by un¬ 
suspected channels, and only become dangerous after a time, 
when they have altered or multiplied in the process of growth. 
Consequently it is of the first importance to know the beginning 
of these maladies, and how to avert them at the outset. Sheep¬ 
raising is one of the most valuable industries, but it has this 
drawback ; that the sheep is a delicate animal and subject to 
decimation by various diseases. Two of the worst of these dis- 
' eases are parasitic—Dropsy-rot, caused by liver-flukes, and the 
Staggers, caused by coenurus cerebralis. In England, the Drop¬ 
sy-rot carries off large numbers of sheep every year, and in the 
epidemic of 1830 the loss was estimated at a million and a half 
of animals. In another epidemic one extensive breeder in the 
isle of Tlianet lost $15,000 worth of sheep from this cause; and 
in France, in 1853 and ? 54, the farmers lost from a quarter to 
three-quarters of their entire flocks. 
This gives us an idea of how much injury may be done and how 
much property may be destroyed by the ravages of minute para¬ 
sites when they become numerous. But the question sometimes 
touches our interest still more closely. The contamination of our 
food by the parasites Cysticereus and Trichina makes the infection 
of domestic animals also dangerous to man. Here veterinary 
pathology and human pathology come together, and there is a 
wide field open for increased usefulness of the veterinay art. 
Take the case of Trichina Spiralis. That parasite was first 
discovered many years ago as an inhabitant of the human mus¬ 
cle. But it was thought to be harmless, because it was only 
found in patients who had survived the original attack and had 
died years afterward, from some other cause. The fatal cases 
were not understood, and were not even recognized at all, as 
produced by the parasite. But at last, by a series of laborious 
