Page:A treatise on diseases of the bones (electronic resource) (IA b21289013).pdf/21

INTRODUCTION. xvi Experiments in animals have not accomplished so much for the elucidation of the reparative processes of bone in man as might probably have been expected. he eir- eumstanecs attendant on the fraetured or necrosed bone, in man, are essentially different from those of the experi- ment of breaking, or causing the death of a bone in ani- mals. Thus, around the fractured bone of an animal, the deposit of cartilaginous and osseous substance, whieh has been designated provisional eallus, is of uniform oeeur- renee. But, in the human subject, no sueh eartilaginous and osseous deposit uniformly takes place around the fractured bone; here, therefore, it is not an essential part of the reparative proeess. Also, with respect to the produe- tion of neerosis by experiment in animals, the condition of the surrounding soft parts is so materially different from the eondition of these parts preceding and aeeompanying the death of the shaft of a bone in man, that, in eonse- quenee, the features of the reparative process in the two eases are essentially different. It has, therefore, been incorrectly assumed, that beeause sueh is the reparative process of fraeture, or necrosis, in animals, it must be so likewise in man.

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