The horse which exhibits bog spavin and thorough-pin also generally shows wind-galls on the hind legs. Let the reader consider the hard usage the limb must have undergone before it could have become thus deranged. Here is a specimen, demonstrating the connection which exists between thorough-pin and bog spavin. It was made in consequence of Mr. Varnell having informed the author that thorough-pin was a bulging out of the synovial sheath, proper to the flexor tendon; and was not, as is generally taught and credited, an enlarged bursa. The author found them to be in accordance with the description he had received: the enlargement called thorough-pin, and the synovial membrane of the hock, had united, and free communication existed between them, in the joint which the writer examined. Nature formed the synovial cavity of the joint as a distinct and separate part. It is usual for teachers to promulgate a maxim that Nature is all-wise. Man, however, it appears, can violently disarrange her provisions; yet, by his fellow-men, he is accounted to have done no wrong who destroys the harmony of Nature. Thorough-pin is not, in popular estimation, essentially unsoundness. A horse thus disfigured is believed, nay, professionally pronounced to be, perfect, although two distinct parts are battered into one. If two are beneficial, why was one only created? The horse may not be lame; but, granting Nature to be all-wise, must not the uses for which the limb was designed be injured? The question is not, whether an animal trots sound; but it is, whether it really is sound. What sane man would assert such to be the case, where the anatomical structures have been disorganized? CAPPED KNEE. =Capped knee=, in the fore limb, answers to bog spavin in the hind leg; the diseases are alike in most respects. Both affect the principal articulation of a complicated joint; both may be provoked by the like causes; but the fore leg, being less exposed to shocks than the hinder member, must have been much abused before it could become thus deformed. [Illustration: THE SYNOVIAL MEMBRANE OF THE KNEE-JOINT ENLARGED.]