338 SPECIAL HISTOLOGY. 



and ligaments, and of the vascular channels; but a more exten- 

 sive new formation of bone, "whether periosteal or in the Haversian 

 systems, together with a simultaneous and more considerable absorption, 

 never occurs in them. It was formerly believed that the coloration of 

 the bones of adult animals by madder, proved that deposition of 

 bone substance continued to take place even in them, it being assumed 

 that newly forming osseous tissue only became colored ; but since it 

 has been shown, that bones already formed were likewise colored by 

 the same agent, and that colored bones in the adult did not lose their 

 color (Brulle and Hugueny), this view becomes untenable. Whether 

 in the perfect bone a change, if not of the elementary parts, but still of 

 the atoms, takes place, the same external figure remaining, is another 

 question, for the solution of which microscopy affords no facts. This 

 much is certain, that the organization of bone is such, that notwithstand- 

 ing the rigidity of their structure, they are in the most general and most 

 intimate relation with the nutritive plasma of the blood. In every situ- 

 ation where the osseous tissue is in connection with vessels, as on the 

 external surface, in the walls of the medullary cavities and cancelli, and 

 those of the Haversian canals, millions of closely crowded minute open- 

 ings exist. These convey the blood-plasma, by means of the canaliculi, 

 into the lacunae lying nearest to the surfaces mentioned, from which it is 

 then conducted by wider canaliculi to the more distant lacunae, as far as 

 the outermost layers of the Haversian lamellae, and those laminae of the 

 great lamellar system which are most remote from the vessels. When 

 the enormous number of the canaliculi and their multifarious anastomoses 

 are considered, it must be allowed that no tissue in the human body is 

 better provided for in respect of the distribution of the blood-plasma, 

 whilst in scarcely any other is the direct conveyance of the fluid to the 

 most minute particles more immediately necessary than in it. There 

 can be no doubt that the fluids, which this " plasmatic vascular system" 

 (Lessing) of the bones, obtains from the bloodvessels, probably some- 

 what modified by the influence of the nucleus which, as I have before 

 endeavored to show, is still retained in every lacunae, are most indis- 

 pensably requisite for the maintenance of the bone ; for we see, that 

 when the supply of blood to a bone is impeded by the destruction of the 



variability in this respect is neither more nor less remarkable than the greater or less fibril- 

 lation of the corresponding element of connective tissue, or than the inconstancy of the dis- 

 position of the cleavage lines of the same element in striped muscle. 



As little is any line of demarcation t to be drawn between primary and secondary bone 

 as regards the tissues from which they proceed. Indifferent tissue, in which calcareous 

 matter is deposited at once, is the basis of secondary bone ; an identical tissue in which 

 to serve a temporary purpose chondrin is deposited, being subsequently withdrawn and 

 replaced by calcareous salts is the basis of primary bone. And this paragraph may 

 serve as an answer to the fourth question. If it be correct, we cannot imagine that any 

 distinction of the bones into primary and secondary, upon the ground of their develop- 

 ment or non-development from cartilage, can be other than arbitrary. TRS/] 



