THE OSSEOUS SYSTEM. 377 



§ 108. 



The vital phenomena exhibited in the mature bones are not, 

 during the vigorous period of life, accompanied with any nota- 



think, that Kiilliker is in the right, as against Reichert, Meyer, and others, when he 

 says that secondary bone is not developed from cartilage, and that, in this respect, it 

 may be distinguished from primary bone. 



2. Though this matrix of secondary bone, however, is assuredly not cartilage, it is 

 another matter whether it is, or is not, morphologically homologous with cartilage. 

 To arrive at any just conclusion on this head, it is necessary to understand the pre- 

 cise structure of this tissue, which Messrs. Tomes and De Morgan have been the first 

 to point out : " If attention be directed to the part furthest removed from the bone, 

 it will be seen that the membrane-like mass is composed of oval cells with slight pro- 

 longations from the extremities, which are frequently arranged in the form of bands 

 of fibrous tissue. Dr. Sharpey has observed that the membrane into which the bone 

 extends is like fibrous tissue in an early stage of development ; and this observation 

 is strictly true when confined to the part indicated, but the analogy ceases [? Eds.] 

 as we extend our examination towards the bone. Here, in the place of cells with 

 elongated processes, or cells arranged in fibre-like lines, we find cells aggregated into 

 a mass, and so closely packed as to leave little room for intermediate tissue. The 

 cells appear to have increased in size at the cost of the processes which existed at an 

 early stage of development and formed a bond of union between them. Everywhere 

 about growing bone, a careful examination will reveal cells attached to its surface, 

 while the surface of the bone itself will present a series of similar bodies ossified. To 

 these we propose to give the name of osteal cells, as distinguished from lacunal and 

 other cells. In microscopic characters, the osteal cells closely resemble the granular 

 cells of temporary cartilage; so closely, indeed, that the latter, when detached from 

 the cartilage, could not well be distinguished from them. They are, for the most 

 part, spherical or oval in form, and lie on the surface of the growing bone in a 

 crowded mass, held together by an intervening and apparently structureless matrix. 

 Here and there we find a cell which has accumulated about itself an outer invest- 

 ment of transparent tissue, and has, in fact, become developed into a lacunal cell 

 destined to become a lacuna" (1. c, p. 23). 



The tissue, then, from which secondary bone immediately proceeds, is composed of 

 a homogeneous matrix, in which, corpuscles, identical with the cartilage-corpuscles, 

 are imbedded (see fig. 136 A, 1, a) : it is therefore identical, as Dr. Sharpey de- 

 scribed it, with young connective tissue; and as we have seen above (note, § 101), 

 and as the authors state, with foetal cartilage. Though not cartilage, therefore, it is 

 homologous with it (as is, indeed, admitted by Professor Kolliker); a fact which is 

 still more strongly evidenced by the transition of cartilage into a similar tissue, at its 

 edges (Tomes and De Morgan, 1. c., p. 24), which may readily enough be observed, 

 and which has been particularly shown by Reichert to occur between the primary 

 and secondary bones of the skull (' Zur Streitfrage iiber die Gebilde der Bindesub- 

 stanz, iiber die Spiralfaser und iiber den Primordial-Schadel,' Midler's 'Arehiv,' 

 1853). 



Now it seems to us that a tissue which is identical with the embryonic form of 



