378 SPECIAL HISTOLOGY. 



ble or active morphological changes. It is true that, during 

 this period, some of the processes above considered go on — such 



cartilage, which passes into adult cartilage, and differs from cartilage only in the 

 absence of chondrin (in which respect ossified cartilage agrees with it), — is in a mor- 

 phological point of view homologous with cartilage. 



3. With respect to the third question, — Sharpey and Kblliker are of opinion 

 that the deposit of calcareous matter and the formation of lacunae take place in the 

 same manner as in cartilage, i. e. that the calcareous salts are deposited evenly 

 through the matrix, leaving spaces round the corpuscles or " nuclei," from which the 

 canaliculi are subsequently developed by resorption. Messrs. Tomes and De Morgan, 

 on the other hand (see passage cited above), maintain that secondary bone differs 

 from primary, in so far as certain of the corpuscles — " osteal cells," — " arrange them- 

 selves side by side, and together with the transparent blastema in which they lie, 

 become impregnated with ossific matter, and permanently fused with the bone-tissue 

 with which they lie in contact. By the linear arrangement of these osteal cells, 

 lamination is produced. In the case of new laminated bone, the cells are simply 

 ossified without arrangement. Lying amongst the osteal cells will be seen some 

 which have accumulated around them a quantity of tissue which forms a thick invest- 

 ment to them ; they then become granular, and take on in every respect the charac- 

 ters of a lacunal cell. These are found deposited at intervals along the line of ossifi- 

 cation, and becoming blended with the general mass, the granular cell remaining as 

 a lacuna, and sending out processes in all directions" (' Abstract in Proceedings of 

 Royal Society'). 



We must confess that all we have seen leads us to believe that the former of these 

 accounts is correct. We have never been able to find evidence of any of the cor- 

 puscles becoming converted into "osteal cells," and we believe, for the following 

 reasons, that this process does not take place. In examining the growing Haversian 

 canals in Man, and particularly in the Calf (fig. 136 A, 1), we have very frequently 

 found the innermost layer transparent, glassy, and structureless — exhibiting nothing 

 but the corpuscles (d) lying in lacunae without canaliculi. This layer would be as 

 much as jjmjth of an inch thick ; in the layer (c) immediately external to it, however, 

 the " osteal cells" were exceedingly well marked. The inner layer looked like smooth 

 ice, and the outer like ice which had cracked into innumerable tolerably even por- 

 tions — but these cracks were by no means produced by the canaliculi, which, as yet, 

 were hardly at all developed. Now it seems clear that if the "osteal cells" were pro- 

 duced by the calcification of certain of the corpuscles, they ought to be more obvious 

 in the young, inner layer, than in the outer; whereas just the reverse occurs. The 

 fact stated by Messrs. Tomes and De Morgan, that lamination is less obvious in 

 young than in old bone, tends to exactly the same conclusion. Again, if the granular 

 substance between the lacunae were composed of calcified corpuscles — " osteal cells," 



the action of acids ought to bring them out as strongly as it does those of the 



lacuna; ; whereas neither in young bone nor in old can anything of the kind be 

 seen. 



With respect to the lacunas, again, we have the same remarks to make as when 

 speaking of cartilage. We have never been able to find any trace of the development 

 of the corpuscles (granular cells) into lacuna?. As to the tissue which accumulates 

 round them and forms an investment, we have frequently observed the appearance 



