292 



extends within a joint or otherwise, and once more, intra-periosteal, 

 when the periosteum remain ititact. And, finally, there is no absolute 

 limit to the use of descriptive terminology in the case. 



The condition of displacement is largely influential in determining 

 the question of treatment, and as afl'ecting the final result of a case of 

 fracture. This, however, is dependent upon its location or whether its 

 seat be in one or more of the axes of the bone, in its length, its breadtb, 

 its thickness, or its circumference. An incomplete fracture may also 

 be either simple or comminuted, the periosteum, in the latter case when 

 it is intact, keeping the fragments together, the fracture in that case 

 belonging to the intra periosteal class. At times, also, there is only a 

 simple fissure or split in the bone, making a condition of much difiSculty 

 of diagnosis. 



Two varieties of originating cause may be recognized in cases of frac- 

 ture. They are the xjredisposing and the occasional. As to the first, 

 different species of animals differ in the degree of their liability. That 

 of the dog is greater than that of the horse, and, in horses, the various 

 questions of age, the mode of labor, the season of the year, the portion 

 of the body most exposed, and the existence of ailments, local and gen- 

 eral, are all to be taken into account. 



Among horses, those employed in heavy draught work or that are 

 driven over bad roads, are more exposed than light-draught or saddle 

 horses, and animals of different ages are not equally liable. Dogs and 

 young horses, with those which have become sufficiently aged for their 

 bones to have acquired an enhanced degree of frangibility, are more lia- 

 ble than those which have not exceeded the time of their adult prime. 

 The season of the year is undoubtedly, though in an incidental way, 

 an important fiictor in the problem of the etiology of these accidents, 

 for though they may be observed at all times, it is during the months 

 when the slippery condition of the icy roads renders it difficult for both 

 men and beasts to keep their feet that they occur most frequently. The 

 long bones, those especially which belong to the extremities, are most 

 frequently the seat of fractures, from the circumstance of their super- 

 ficial position ; their exposure to contact and collision, and the violent 

 muscular efforts involved both in their constant rapid movement and 

 their labor in the shafts or at the pole of heavy and heavily laden car- 

 riages. 



The relation between sundry idiosyncrasies and diatheses and a 

 liability to fractures is too constant and well established a pathological 

 fact to need more than a passing reference. The history of rachitis, of 

 melanosis, and of osteo-porosis, as related to an abnormal frangibility of 

 the bones, is a part of our common medical knowledge. There are few 

 persons who have not known of cases among their friends of frequent 

 and almost spontaneous fractures, or at least of such as seem to be pro- 

 duced by the slightest and most inadequate violence, and there is no 

 tangible reason for doubting an analogous condition in individuals of 



