THE OSSEOUS SYSTEM. 337 



morphological changes. It is true that, during this period, some of the 

 processes above considered go on such as the enlargement of the 

 sinuses in the cranial bones, of the points of insertion of muscles 



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 morphological point of view 

 homologous with cartilage. 



3. With respect to the third question, Sharpey and Ko'lliker are of opinion that the 

 deposit of calcareous matter and the formation of lacunas 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 deve- 

 loped 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 corpus- 

 cles "osteal cells/' "arrange themselves 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 investment to them ; they then 

 become granular, and take on in every respect the characters of a lacunal cell. These are 

 found deposited at intervals along the line of ossification, and becoming blended with the 

 general mass, the granular cell remaining as a lacuna, and sending out processes in all direc- 

 tions" (" 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 corpuscles 

 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 par- 

 ticularly in the Calf, we have very frequently found the innermost layer transparent, glassy, 

 and structureless exhibiting nothing but the corpuscles (e?) lying in lacuna? without canali- 

 culi. This layer would be as much as ^^thof an inch thick; in the layer (r) 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 portions 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 lacunae, 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 corpus- 

 cles (granular cells) into lacunae. As to the tissue which accumulates round them and forms 

 an investment, we have frequently observed the appearance described ; but this investment 

 was nothing but the clear, often homogeneous, calcareous matter, gradually encroaching on 

 the matrix and enclosing the corpuscles. 



We consider, then, that the process of ossification in primary and secondary bone is iden- 

 tical; the deposition of the calcareous matter in granules or as a homogeneous infiltration, 

 being of no constancy or importance. In each case the deposit takes place in the matrix, 

 and leaves spaces (lacunas) round the corpuscles (nuclei, granular cells). Subsequently, the 

 canaliculi are developed in the matrix by a process of resorption ; while their walls and 

 those of the lacuna? may or may not become chemically differentiated from it. At the same 

 time, the matrix may or may not break up into lamina? and " osteal cells" or granules. Its 



22 



