CHAPIER 1I¥4 
INTE STINA PARASITE &: 
Bots. Ascaris Megalocepha, or Large-headed Lumbricoid Worm. Oxyuris 
Curvula, or Maw Worm. Strongylus Tetracanthus, or Four-Spined 
Strongyle. Strongylus Armatus, or Armed Strongyle. Echinococcus 
Veterinorum, or Common Hydatid of the Horse. 
ALTHOUGH one is generally disposed to hear and speak of worms with 
anything but pleasurable feelings, we need -hardly tell our readers that there 
are few creatures, whose development and growth are more wondrous or 
more interesting, than that of the several intestinal parasites. It is not, 
however, our purpose to enter deeply into the life histories of these creatures, 
but to cast a glance over the modes of their living, and to describe in 
as simple a manner as we are able, the methods to.be adopted in order to 
rid the horse of his self-invited guests. We shall treat of six different 
varieties of internal parasites. The other kinds are so rarely met with, as 
to require no description at our hands. 
’ The first of the parasites of the horse of which we have to speak is the 
common gad-fly, or cestrus equi, whose larval form is the bot. All our readers 
have heard of the gad-flies, which prove so irritating to oxen by piercing 
through their hides. The female gad-fly settles on its victim while out at 
grass, late in the summer, not for the sake of deriving sustenance for herself, 
but for that of providing .a suitable habitat for her eggs. It is at this 
time of the year that she deposits her eggs on the hairs of the coat, and this 
she is enabled to do by means of a thick, sticky fluid. The fly generally 
selects, as sites for depositing her eggs, those parts of the horse which the 
animal can reach easily with the tongue, namely the shoulders, the lower 
part of the neck, and the inner parts of the forelegs, especially around the 
knees. The horse frequently licks the portion of coat on which the eggs 
have been deposited. They gradually become hatched in about three weeks 
from the time of their deposition by the gad-fly, and the larval form or 
maggot makes its escape out of its enclosing egg-shell. The maggots are 
. then carried to the horse’s mouth, and ultimately to his stomach along with 
“his food and drink. Necessarily, as Professor Williams points out, many larvze 
perish during this passive mode of immigration ; some being dropped from 
the mouth, and others being crushed in the food during mastication; but 
