92 BONE. 



and contains, in 100 parts, 9G of fat, 1 of connective tissue, and 3 of 

 water. In short bones, and in the cancellated ends of long bones, but 

 especially in the cranial diploe, the bodies of the vertebra, the sternum, 

 and the ribs, it is red or reddish in colour, of more fluid consistence, 

 and with very few fat-cells. That from the diploe consists of 75 parts 

 of water and 25 of solid matters, which are chiefly albumin, fibrin, 

 extractive and salts, with mere traces of fat. "While, however, the fat- 

 cells are scanty in the red-coloured marrow, it contains numerous 

 roundish nucleated cells — the proper marrow cells of Kolliker. These, 

 Avhich in general appearance resemble the pale corpuscles of the blood, 

 and lilce them exhibit amoeboid movements, are supported by a fine 

 reticulum of connective tissue. They vary somewhat in size, and many 

 of them present a reddish colour, resembling somewhat in appearance 

 the nucleated primitive red corpuscles of the embryo; indeed, it is stated 

 that ordinary red-blood corpuscles are produced from them (Neumann, 

 Bizzozero). Other cells have occasionally been noticed containing 

 one or more red corpuscles in their interior : whether these have been 

 ■developed iti situ in a manner similar to that previously described in 

 connective tissue corpuscles of the young animal, or have been taken 

 into the interior of an amoeboid cell, there to be transformed into pigment 

 granules, is not certainly known. Cells containing reddish pigment 

 granules are, however, not uncommon. In addition to these smaller 

 cells, and larger ones which resemble connective tissue-corpuscles, 

 there occur in the marrow, especially in the neighboui'hood of the 

 osseous substance, large multi-nucleated protoplasmic masses (myelo- 

 plaques, Robin), which, as pointed out by Ktilliker, appear to be more 

 •especially concerned with the process of absorption of bone, under which 

 they will consequently be described. 



Blood-vessels. — The bones are well supplied with blood-vessels. A 

 network of periosteal vessels covers their outward surface ; others pene- 

 trate to the cavities of the spongy part and the medullary canal^ on the 

 sides of which they ramify ; and fine vessels, deprived of their muscular 

 coat, run through all parts of the compact tissue in the Haversian canals. 

 The sides of these internal cavities and canals make up together a large 

 extent of inward surface on which vessels are spread. The nutritious 

 fluid conveyed by these vessels no doubt escapes through their coats 

 and permeates the surrounding dense bone interposed between the 

 vascular canals, and it seems highly probable that the system of lacunar 

 and communicating canaliculi, already described, is a provision for 

 conducting the exuded fluid through the hard mass. When a bone is 

 macerated, its vessels and membranes are destroyed, whilst the inter- 

 mediate true bony matter, being of an incorruptible and persistent 

 nature, remains ; a process which, for obvious reasons, cannot be effected 

 with the soft tissues of the body. 



The vessels of bone may be recognised while it is yet fresh by the 

 colour of the blood contained in them ; but the vascularity of 

 the tissue is rendered much more conspicuous by injecting a limb 

 with size and vermilion, depriving the bones of their earth by 

 means of an acid, and then drying them and putting them into 

 oil of turpentine, by which process the osseous tissue is rendered 

 transparent whilst the injected matter in the vessels retains its red 

 colour and opacity. Numberless small vessels derived from the 

 periosteum, as already mentioned, pass along the Haversian canals 



