THE THYMUS GLAND. 175 



wnund will then readily heal by the use of turpentine dressings, more or less stiiuu- 

 lalini^. accordinor to circumstances. 



Saddle galls are tumours, and sometimes galls or sores, arising also from the pres- 

 pure and cliaiing of the saddle. They differ little from the warble, except that there 

 is very seldom the separation of the dead part in the centre, and the sore is larger and 

 varying in its form. The ajiplication of cold water, or salt and water, will generally 

 remove excoriations of this kind. 



With regard, however, to all these tumours and excoriations, the humane man will 

 have the saddle eased and padded as soon as it begins to be of the least inconvenience 

 to the horse. 



MUSCLES OF THE BREAST. 



There are some important muscles attached to the breast connected with that 

 expansion of the chest which every horse should possess. In the cut, page 159, are 

 seen a very important pair of muscles, the pedorales transversi, or pectoral muscles, 

 forming two prominences in the front of the chest, and extending backward between 

 the legs. They come from the fore and upper part of the breast-bone ; pass across the 

 inward part of the arm, and reach from the elbow almost down to the knee. They 

 confine the arm to the side in the rapid motion of the horse, and prevent him from 

 being, what horsemen would call, and what is seen in a horse pushed beyond his 

 natural power, " all abroad." Other muscles, pedorales magvi et parvi, the great 

 and little pectorals, rather above but behind these, go from the breast-bone to the 

 arm, in order to draw back the point of the shoulder, and bring it upright. Anotlier 

 and smaller muscle goes from the breast-bone to the shoulder, to assist in the saiue 

 office. A horse, therefore, thin and narrow in the breast, must be deficient in import- 

 ant muscular power. 



Between the legs and along the breast-bone is the proper place in which to insert 

 rowels, in cases of inflamed lungs. 



CHEST-FOUNDER. 



These muscles are occasionally the seat of a singular and somewhat mysterious 

 disease. The old farriers used to call it anticor and chest-founder. The horse has 

 considerable stiffness in moving, evidently not referable to the feet. There is tender- 

 ness about the muscles of the breast, and, occasionally, swelling. We believe it to 

 be nothing more than rheumatism, produced by suffering the horse to remain too long 

 tied up, and exposed to the cold, or riding him against a very bleak wind. Some- 

 times a considerable degree of fever accompanies this; but bleeding, physic, a rowel 

 in the chest, warm embrocations over the parts affected, warm stabling, and warm 

 clcithing, with occasional doses of antimonial powder, will soon subdue the complaint. 



CHAPTER VII. 

 THE CONTENTS OF THE CHEST. 



THE THYMUS GLAND. 



At the entrance of the trachea into the thorax, and ere it has scarcely penetrated 

 between the first ribs in the young subject, it comes in contact with an irregular glan- 

 dular body, situated in the doublinnr of the anterior mediastinum. It is " tiie thymus 

 gland," or, in vulgar language, the sweet-bread. In the early period of utero-gesta- 

 tion, it is of very inconsiderable bulk, and confined mosth^ to the chest ; but, during the 

 latter months, it strangely developes itself, — the superior cornua protrude out of the 

 thorax and climb up the neck, between the carotids and the trachea. They are evi- 

 dently connected with the thymus gland, and become parts and portions of the parotiil 

 glands. 



We are indebted to Sir Astley Cooper for the best account of the anatomical struc- 

 »are, anil possible function of the thymus gland. It presents, on being cut into, a 



