CHAP. V.] 



OSSIFICATION. 



119 





Vertical section from the same specimen as fig. 30, but deeper 

 in the bone, shewing the cancell! with blastema and a few 

 cartilage-cells, and also the osseous laminae containing lacunae, 

 S j mi i ar to the nuclei of thecells: d. Seen by a low power. 

 &. Portion of d more highly magnified. /. Blastema around 

 lhe cartilage-cells, e. Cartilage-cell apposed to the wall, and 



fig. 30. If the specimen 

 be examined deeper in 

 the bone, even at a depth 

 of -jL or Y 1 ^ of an inch, 

 other appearances are met 

 with. The lamellae of 

 bone enclosing the can- 

 celli are no longer simply 

 homogenous or finely 

 granular in texture, but 

 have acquired more the 

 aspect of perfect bone. 



They are also thicker, and its nucleus ready to become similar to the otlier lacuna3 ' as * 

 include in their substance elongated oval spaces, which, excepting 

 that they are of a roughly granular nature, exactly resemble the 

 lacuna of bone already described. They are evidently the nuclei 

 of the cells of the temporary cartilage. They are scattered at pretty 

 uniform distances apart, and they all follow Fig.s3. 



the direction of the lamellae to which they 

 belong (fig. 32, d, g). The curvilinear out- 

 line of their now ossified cells can often be 

 partially discerned (fig. 32, e) . 



Within the cancelli, only a few cells can be 

 detected, these cavities being chiefly occupied 

 by a quantity of new substance, consisting of 

 granules, and resembling a formative blastema 

 or basis, like that out of which all the tissues 

 are evolved (fig. 32, /, and fig. 33, ). The 

 cells that are met with are in apposition with 

 the wall; and sometimes (as in fig. 32, e)one 

 of them seems half ossified, and its nucleus 

 about to become a lacuna. The nuclei of 

 these cells have now always the same direc- 

 tion as the neighbouring lacunas. 



In fig. 33, taken from a little deeper in 

 the bone, we have portions of three cancelli, 

 1. 1. 1., together with the osseous material, now f^r'S: 

 of considerable thickness, that intervenes be- 

 tween them. In the centre of this last is 

 seen a lamella, /, of a peculiar kind, contain- 

 ing no lacunae, and quite distinct from the P earance oftcn seen7 " 

 layers, h. h., between which it lies. These consist of nucleated 



Another portion from the same 



BWtt? 



