THE OSSEOUS SYSTEM. 347 



part, ultimately becomes ossified, and constitutes all the bones 

 of the trunk and extremities, and a great part of those of the 

 cranium. All these bones are ossified, essentially, in the same 

 way. At one or more points {puiicta ossificationis), in theii 

 interior, a deposition of calcareous matter commences, simul- 

 taneously with a change in the cartilaginous elements ; which 

 transformation proceeds on some, or on all sides, continually 

 converting additional portions of the cartilage into bone. 

 Whilst this is going on, the cartilage, in most cases, ceases to 



5, 8, are nucleated corpuscles from the Kitten and Rabbit; 6, "jagged" corpuscles 

 from the Kitten. 



When Virchow, however, describes the passage of these "cells" into the branched 

 or stellate corpuscles of fibro-cartilage, and considers the latter to be metamorphosed 

 cartilage-corpuscles, he confounds together things which are essentially different. 

 Careful examination of fetal fibro-cartilage, e. g. the intervertebral fibro-cartilage of the 

 Kitten, shows that the stellate body is t lie vail of the cartilage cavity, with processes 

 which run out from it, the original corpuscle remaining in the interior of the cavity, 

 either unchanged or becoming gradually lost, or fused into one mass with its walls. 



The account of the structure of cartilage given by Tomes and De Morgan (1. c, 

 pp. 15, 16) in all essential points agrees with that of Virchow. They call the cor- 

 puscles, granular cartilage cells. 



To recapitulate : — the facts contained in other observations, as apart from the inter- 

 pretation, appear to agree perfectly with our own ; the result of which is, that in the 

 fetal state, cartilage is composed of a homogeneous matrix, in which lie the cor- 

 puscles, in cavities which they just fill ; that their relation to the matrix is exactly 

 that of tiie primordial utricles to the cellulose wall in plants, and that like this they 

 may or may not develope a nucleus ; that witli age they enlarge, but not so fast as 

 the cavities, the walls of which become chemically altered into chondrin, a change 

 which often takes place in such a manner as to give rise to a lamination or to a differ- 

 ence in composition of the inner and outer portions. If the cartilage be converted 

 into fibro-cartilage, the outer part becomes changed into collagen, while an altera- 

 tion into a substance resembling elastic fibre, is effected in the inner portion, and in 

 the direction of certain lines radiating from it, just as we have seen the elastic element 

 to be developed in connective tissue (see § on Connective Tissue). 



So much for the structure of cartilage: with regard to its development and 

 multiplication we must equally demur to the statements in the text. It is, indeed, 

 very true, that no new cartilage -cells arise independently of those which pre-exist; 

 but in opposition to Professor Kolliker we must agree with Leydig, Robin, Remak, 

 and Tomes and De Morgan, that the multiplication of the cartilage-cells invariably 

 takes place by a process of division exactly analogous to that which occurs in plants. 

 So far as we have seen (and in ossifying cartilages, and in that of the Skate, it is 

 easy to trace the process), the corpuscles first become constricted (fig. 129 A, 3), 

 being found occasionally of an hour-glass shape ; and eventually divide (2, 3, 4, 7). 

 The matrix then grows in, so as to separate the two, and the process of fission is 

 complete. — Eds.] 



