380 SPECIAL HISTOLOGY. 



channels; but a more extensive 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 coloured; 

 but since it has been shown, that bones already formed were 

 likewise coloured by the same agent, and that coloured bones in 

 the adult did not lose their colour (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 organisation of bone is such, that notwith- 

 standing the rigidity of their structure, they are in the most 

 general and most intimate relation with the nutritive plasma 

 of the blood. In every situation where the osseous tissue is in 

 connection with vessels, as on the external surface, in the Avails 

 of the medullary cavities and cancelli, and those of the 

 Haversian canals, millions of closely crowded minute openings 

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

 canaliculi, into the lacunae lying nearest to the surfaces men- 

 tioned, from which it is then conducted by wider canaliculi to 

 the more distant lacunas, 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 necessaiy than in it. There can 

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

 system" (Lessing) of the bones, obtains from the blood-vessels, 

 probably somewhat modified by the influence of the nucleus 



primary bone. And this paragraph may serve as an answer to the fourth ques- 

 tion. If it be correct, we cannot imagine that any distinction of the bones into 

 primary and secondary, upon the ground of their development or non-development 

 from cartilage, can be other than arbitrary. 



