COMPOSITION OF BONES, 61 



under our eyes preparations showing them; some of which de- 

 monstrate the fibres running principally longitudinally, others 

 spirally, like the grain of a twisted tree, and others having a 

 mixed course. Upon the whole, the description cited from 

 Meckel, exhibits this subject in a just and accurate manner. 



The more obvious arrangement of the cellular and compact 

 structures of the bones* indicates a considerable difference in 

 their intimate texture: they are, nevertheless, closely allied; 

 for one structure is converted, alternately, into another by dis- 

 ease, of which specimens abound in. the Wistar Museum. In 

 both cases, from the fibres or filaments are formed cells which 

 exist every where, and are only larger and more distinct in 

 what we call the cellular structure; but the compact part has 

 also its cells, though they are smaller, more flattened, and for 

 the most part microscopical* 



Organization of Bones. The blood vessels of the bones, 

 though small, are very numerous. This is well established, by 

 the success of fine injections, which in the young bone commu- 

 nicate a general tinge; and by scraping the periosteum from 

 living bones, whereby their surface in a little time becomes co- 

 vered with blood, effused from the ruptured vessels. In those 

 operations for exfoliation from the internal surfaces of the cy- 

 lindrical bones, where it is necessary to excavate the bone ex- 

 tensively, in order to remove all the detached pieces; unless the 

 general circulation of the limb be previously arrested by the 

 tourniquet, the cavity of the bone is flooded with blood. Bi- 

 chat has also remarked, that the blood vessels of the bones be- 

 come unusually turgid and congested, in cases of drowning and 

 strangulation. The observations in 1832, on cholera in Paris, 

 showed the same congestion of black blood, to have been pro- 

 duced by that disease. 



The arteries which supply the bones, from their mode of dis- 

 tribution, are referred to three classes. The most numerous 

 and the smallest, are those which penetrate from the periosteum, 

 by the capillary pores found over the whole surface of the 

 bones. The next are those which penetrate the larger forami- 

 na at the extremities of the long bones, and at different points 

 of the surface of others. And the third class, called nourish- 

 ing, amounts to but one artery for each of the cylindrical bones 



VOL. L 6 



