DEYELOPMEXT OF HYALIXE CARTILAGE. 



77 



latter case a cell becomes siuToimdcd by many concentric capsules formed in 

 succession ; that is. the first capsule is expanded, and the others fonned each 

 within its expanding predecessor, so that the cartilage comes to consist of scattered 

 cells, each M'ith a concentric system of capsules, which by means of re-agents 

 may be rendered visible in the neighboui-hood of the cells, but fmther otf are 

 inseparably blended into a unifonn substance. '\Mien, on the other hand, the 

 cells have a tendency to frequent subdivision, the new capsules are produced by 



Fig. 46. 

 C 



Fig. 46. — Ideal Plan of the ^Multiplication of Cells of Cartilage. 



A, cell in its capsule ; B, divided into two, each with a capsule ; C, primary capsule 

 disappeared, secondary capsules coherent with matrix ; D, tertiaiy division ; E, secondary 

 capsules disappeared, tertiary coherent with matrix. 



the new cells, and are included in and finally blend with those ^^■hich had be- 

 longed to the previous cells, as shown by fig. 46. 



The matrix, although thus formed of the capsules, becomes to all appearance 

 homogeneous : but in sections of cartilage that have been exposed to acids and 

 other re-agents, the contoiu: lines of the capsules round cells and cell-gioups 

 may be more or less distinctly brovight into view. But, whilst admitting tliat the 

 capstdes have a share in the production of the matrix, Kolliker and some other 

 histologists incline to the opinion that part of it is an independent deposit. 

 Heidenliain, however, found that, when thin sections of cai-tilage are digested 

 for twenty-four hours in water, at from 112° to 122° F., or in diluted nitric acid 

 with clilorate of potash for a gTcater or less time according to the degree of 

 dilution, the matrix becomes parted or marked off into polygonal areas corres- 

 ponding to the larger groups of cells, and these again into smaller groups or 

 single cells, without any intervening substance : the whole matrix thus appearing 

 to be portionea out into segments, each appertaining to a larger or smaller gi'oup 

 of cells, and in all probability representing the aggregated caiDsules belonging 

 to them. 



The vital changes Mhich occur in cai'tilage take place very slowly. Its mode of 

 nutrition has been already referred to ; it is subject to absorption, and when a 

 portion is absorbed in disease or removed by the knife, it is not regenerated. 

 Also, when fractured, as sometimes happens with the rib-cartilages, there is no 

 re-union by cartilaginous matter, but the broken surfaces become connected, 

 especially at their cii'cumference, by fibrous or dense areolar tissue, often by a 

 bony clasp.* But, notwithstanding that normally it is not regenerated, hyaline 

 cartilage occurs in perfectly characteristic fonn as a morbid product in certain 

 tumours. 



* Recent observations tend to show that, in animals at least, the connective tissue 

 which in the first instance joins the ends of a divided rib-cai'tilage eventually becomes 

 its'elf transformed into true hyaline cartilage (Archangeisky, Barth. ) 



