CHAP. V.] 



OSSEOUS TISSUE. 



109 



Fig. 22. 



its interstices; but this lie considers to require confirmation. 



frequent apperance of 



the granular texture is 



well represented in fig. 



22. 



Where bone exists 

 naturally in an exceed- 

 ingly attenuated form, 

 it may consist of a 

 mere aggregation of 

 these granules, impe- 

 netrated by any per- 

 ceptible pores. This 



r . Two lacunae of osseous tissue, seen on their surfaces, shewing 



Constitutes the Simplest the disposition of their pores. The granular aspect of the tissue 



,. , , both on their walls and around them is well represented. Ma^ni- 



lOrm Under Which the fied 1200 diameters. Drawn from a preparation of the cancelli of 



the Femur made by Mr. Tomes. 



tissue can present itselt. 



But all the osseous tissue with which the human anatomist is con- 

 cerned is of such bulk as to contain the series of pores and cavities 

 already alluded to for the conveyance of fluid from and to its vas- 

 cular surface. These pores always advance into the bone from 

 open orifices on its surface. They soon arrange themselves in sets, 

 each of which, after anastomosing with neighbouring ones, dis- 

 charges itself into a small cavity or lacuna, in which its individual 

 pores coalesce. From the sides of this 

 lacuna other pores pass off to similar 

 cavities in the vicinity, and others pro- 

 ceed from its opposite surface to pene- 

 trate still deeper into the tissue. These 

 pour themselves into another lacuna, or 

 divide themselves between two or three, 

 which are connected in like manner by 

 lateral channels. From these again 

 pass others, which pursue an onward 

 course from the surface; and so on, un- 

 til the whole substance of the bone is 



TlPrfnrntpfl 

 the flirtllpr 



Fig. 23. 



tTipm Thp nnrp frnm Transverse section 

 mem. 11C pOl Om bone surround 



g an 



of a part of the 

 HaverMun canal, 



nf thp PYtrpTnp lnpnTi shewing the pores commencing at the 

 L llie exire .e lacunae sur f acei a , anastomosing ami passing from 

 PltVlPr nnpn rm rlip nrfipp nf tViA Vrmo avit y to cavity. Magniried about 300 



[ tne Done diame ters. From a preparation made by 



which they may now have reached, or *** Tome8 ' 

 else take a recurved direction back into the tissue. 



When this beautiful system of microscopic pores and cavities 

 was first seen, it was not recognised as such. The lacunae were 



