GERDY ON THE INTIMATE STRUCTURE OF BONE. 27 



from the divisions of the nutritious foramina, which transmit 

 the medullary vessels of the long bones, but chiefly from the 

 vascular (Haversian,) canals of the compact tissue, as seen in 

 a vertical section of the femur and tibia, fig. 2 and fig. >J. where 

 the increase of the canaliculated structure is in inverse propor- 

 tion to the thickness of the compact. These canals unite together, 

 and divide again and again, so that they become increasingly 

 numerous as they approach the spongy extremities, when they 

 separate from each other and spread out so as to form a large 

 part of these extremities. 



The cellular or areolar tissue of Gerdy, is formed in the 

 thick bones and the extremities of the long bones by the inter- 

 ruptions of the canaliculated tissue, by other canals arising from 

 the surface of the bone which cross them in an angular direc- 

 tion, so as to form quadrilateral cells, see Fig. 3, No. 1, the par- 

 titions of which are pierced, so that there is a free communica- 

 tion between the vessels lining the different cells. 

 The reticulated tissue which was confounded by Bichat with 

 the canaliculated, should be now as it was before his time dis- 

 tinguished from it. So far from being formed of a canaliculated 

 tissue for the purpose of containing vessels, it consists only of 

 a network of bony filaments for the purpose of supporting a 

 delicate cellular membrane called the medullary which is 

 thrown into the form of cells to retain the fat or marrow, and 

 which is very vascular. It is found chiefly in the cavities of 

 the long bones, and terminates short of the extremities in a 

 point, see Fig. 3, 6, while the canaliculated tissue continues to 

 expand. This tissue is beautifully developed in the long bones 

 of the horse, but scarcely exists at all in those of the bullock. 

 - Vessels of the bones. All anatomists admit three kinds of 

 vessels in the bones ; those of the compact tissue, those of the 

 cellular tissue, those of the medullary canal. 

 Those of the compact tissue are very fine and very nume- 

 rous ; they, penetrate it in great numbers, after having divided 



Very generally it is deficient in places on the articular surface of bones, so as to 

 leave the cells of the spongy tissue and their vascular canals naked when the 

 cartilage is removed. 7. Internal malleolus. p. 



