MANGE. 921 
health rather than as the declaration of that state which the majority 
of mankind are pleased to term perfect condition. The animal which 
escapes must be of so sound a body as to afford no nutriment to the 
disorder which preys upon debility. Probably not one horse in ten 
thousand could resist so searching a test; the trial, however, after all, 
would be no more than a negative proof; and it is to be much regretted 
that science, up to the present time, has not discovered any means by 
which the presence of established health can be demonstrated. 
Mange depends upon the presence of an insect which is classed with 
spiders, though to the uninitiated it looks, under the microscope, far 
more like a deformed crab. A representation of this parasite, very 
highly magnified, is here given, from Dr. Eras- 
mus Wilson’s paper upon the subject; and the 
reader may indulge his ingenuity by discovering 
its likeness to the spider. 
The parasites are, when attentively searched 
for, to be recognized by the naked eye. Any 
man, by scratching the roots of the hair upon 
the mane of a mangy horse, may loosen a por- 
tion of scurf; let this scurf be received or cast [ ma 
upon a sheet of white paper. The paper then 
should be subjected to a strong light; the glare 
of the noonday sun is to be preferred, as warmth 
greatly influences the activity of the parasites. 
Numerous very small shining points may thus 
be seen moving about the mass in all directions. Those points are the 
insects, and, considering the easy means we now possess of demonstra- 
ting their existence, it seems astonishing that veterinary science was so 
long before it recognized the true source of the contagion. Even at 
the last moment, the sight was quickened by the research of a human 
physician, Dr. Erasmus Wilson; but after that gentleman soon followed 
Mr. Ernes, veterinarian, of Dockhead. 
Mange would be far less general than it is, did not the convenience or 
the prejudice of mankind predispose them to favor a “run at grass.” 
The horse there placed is all at once taken from a stimulating diet, 
while, the groom being relieved of his charge, foulness accumulates upon 
the coat. The animal, instead of standing still and feeding upon nour- 
ishing provender, has to travel far and to distend the stomach with a 
watery substance before the cravings of hunger can be appeased and 
satiety impress the creature with a consciousness that existence has 
gathered a sufficient support. The quadruped while at grass is neces- 
sitated to be eating the major portion of both day and night; little 
THE MANGE INSECT. 
