281 



given, containing only the briefest hint of matters which, though not 

 necessarily in their ultimate scientific minutiae, must be clearly com- 

 prehended in order to acquire a symmetrical and satisfactory view of 

 the theme as a practical collation of facts to be remembered, analyzed, 

 applied, and utilized. 



It was th-e great Bacon who wrote : ' ' The human body may be 

 compared, from its complex and delicate organization, to a musical 

 instrument of the most perfect construction, but exceedingh' liable 

 to derangement." In its degree the remark is equally applicable to 

 the equine body, and if we would keep it in tune and profit by its 

 harmonious action Ave must at least acquaint ourselves with the rela- 

 tions of its parts and the mode of their co-operation. 



ANATOMY. 



The bones, then, are the hard organs which in their connection and 

 totality constitute the skeleton of an animal. They are of various 

 forms, of which three — the long, the flat, and the small — are recog- 

 nized in tlie extremities. These are more or less regular in their form, 

 but i^reseut upon their surfaces a variety of aspects, exhibiting in 

 turn, according to the requirement of each case, a roughened or 

 smooth surface, variously marked with grooves, crests, eminences, and 

 depressions, for the necessary muscular attachments, and, as before 

 mentioned, are connected by articulations and joints, of which some 

 are immovable and others of a movable kind. 



The substance of the bones is composed of a mass of combined 

 earthy and animal matter, surrounded by a fine, fibrous enveloping 

 membrane (the periosteum) which is intimately adherent to the 

 external surface of the bone, and is, in fact, the secreting membrane 

 of the bony structure. The bony tissue proper is of two consistencies, 

 the external portion being hard and " compact," and called by the 

 latter term, while the internal, known as the ' ' spongy tissue " or 

 " areolar," is also of a consistency corresponding with these descrip- 

 tive terms. Those of the bones which possess this latter consistency 

 contain also, in their spongy portion, the medullary substance known 

 as marrow, which is deposited in large quantities in the interior of 

 the long bones, and especially where a central cavity exists, called, 

 for that reason, the medullary cavity. The nourishment of the bones 

 is effected by means of what is known as the nutrient foramen, which is 

 an opening established for the jjassage of the blood vessels which con- 

 vey the necessary nourishment to the interior of the organ. There 

 are other minutiae concerning the nourishment of the skeleton, such 

 as the venous arrangement and the classification of their arterial ves- 

 sels into several orders, which, though of interest as an abstract study, 

 are not of sufficient practical value to refer to here. 



The active organs of locomotion, the muscles, form, speaking gen- 

 erally, the fleshy covering of the external part of the skeleton and 



