174 



MANUAL OF HISTOLOGY. 



We now know that cartilage hardly ever becomes bony tissue, but on 

 being calcined, it has rather attained the end of its course, and neither 

 grows nor is further developed in any other manner. In this form it may 

 exist for a longer or shorter period, and, in many of the lower animals, the 

 whole life through, or, more frequently still, it may undergo a rapid re-solu- 

 tion, in order to make way for the formation of true osseous tissue. 



We are indebted to Bruch, but more even to H. Mutter, for having 

 first enlightened us as to the right way of viewing these processes. 



In some rare cases it is 

 the cells (a-e) which are 

 first affected by calcifica- 

 tion (fig. 165), but more 

 commonly the ground- 

 mass (/). Later on, we 

 see both parts equally at- 

 tacked by it, or perhaps 

 the process may con- 

 fine itself principally to 

 the intercellular sub- 

 stance. This process 

 consists in the deposit 

 of either finely granular, 

 or, what is more rare, of 

 coarser crumbs and mole- 

 cules of the salts of lime. 

 The tissuebecomes, owing 

 to this, more and more 

 opaque, until, finally, it is 

 so in an extreme degree. 

 Touching the cartilage- 

 cells, those whose cap- 

 sules are apparent, still as 

 well as those where the latter have been merged into the ground-sub- 

 stance, may become the seat of the deposition of lime-salts. Thinly cap- 

 suled cells show us the molecules more on the interior of the enve- 

 lope, or perhaps in its cavity also (e). If the capsule be stronger (a, &, c\ 

 it is impregnated with calcareous salts, while the real cell usually remains 

 soft. When daughter-cells are present (g, above), we frequently remark, 

 beside the calcification of the parent-capsule, a deposit of salts in the 

 layers of the secondary envelopes. 



If the deposition take place regularly in the ground-substance, the 

 granules of lime are (especially at first) arranged in groups around the 

 cells (fig. 165, g, below, and 166, a). Later on their amount increases 

 more and more in the rest of the matrix (fig. 166, b t c, d) until at last 

 they may appear heaped up, molecule on molecule, in the closest contact 

 with one another (fig. 165, /). 



This calcification of cartilaginous tissue occurs in the first place to a 

 very great extent in the embyronic and earlier periods of life, appearing 

 there in the falsely-called ossification of cartilage. Cartilage of this 

 kind soon becomes dissolved. 



On the other hand, this same process appears subsequently as an ordi- 

 nary occurrence in the so-called permanent cartilage of later life ; for in- 

 stance in that of the ribs and larynx. Calcified masses of the last kind 



Fig. 165. Diagrammatic sketch of calcified cartilage, a, A cap- 

 su'e with thick walls and shrivelled contents; 6, another, wirh 

 daughter-cells; c. with very thick walls ; d, very markedly calci- 

 fied ; e, cell with a thin memhrane undergoing calcification; /. 

 a piece of cartilage with molecules of lime between and around 

 the cells; g. another, in which the granules surround the cell 

 more completely. 



