THE FORE LEGS. 105 



stomach ; (see fig. 4,) and so tenaciously do they adhere, 

 that the hook will break before they leave their hold. 

 There these pests contrive to locate during the whole winter, 

 and to the end of the following spring, feeding on the 

 mucus ; by which time they have grown to full size, (fig. 5,) 

 and must now undergo a new transformation ; they quit 

 their hold of the coating of the stomach, are carried into the 

 villous portion along with food, from thence pass into the 

 intestinal canal along with the chyme, and at length are 

 discharged with it. The caterpillars thus evacuated seek 

 an appropriate place in the ground, where they assume 

 the imago or chrysalis condition ; and remaining in this 

 state for some weeks, at length break out from their swathing 

 and assume the form of the perfect insect. Immediately 

 after this the males and females pair ; the latter becoming 

 impregnated, set about seeking an appropriate situation where 

 to deposit their eggs, which, in imitation of the parent, by a 

 peculiar instinct, they fix on the hairs of a horse, from whence 

 they are licked off and swallowed in the larva state. 



There are two species of gad-flies, the second is known 

 by the name of the red bot, fig. 6 is its larva, and fig. 7 the 

 perfect fly. Their natural history and habits are similar 

 in all respects to the other. 



CHAPTER V. 



DISORDERS OF THE EXTERNAL PARTS OF THE HORSE. 



SECTION I.— The Fore Legs. 



We come now to treat of those portions of the framae of a 

 horse most intimately connected with his action, and his 



r 



