ITS HISTOLOGICAL RELATIONS. 43 



articular cartilages of the lower jaw, of the sterno-clavicular 

 articulation, and of the wrist-joint, consist of true but very solid 

 fibrous connective tissue, inclosing true cartilage cells, in addition 

 to a few nuclear fibres, We cannot wonder, therefore, that (as 

 connective tissue always yields glutin) these cartilages should, on 

 boiling, yield ordinary glutin or bone-gelatin, notwithstanding the 

 presence of cartilage-cells. 



Donders distinguishes a third kind of fibre-cartilage, which he 

 terms elastic ; to this class belong the cartilages of the larynx, and 

 the external ear, and the cartilage investing the condyle of the 

 lower jaw. These structures consist of a dense tissue of fine elastic 

 fibres, in which isolated cells are inclosed. These fibres are not 

 altered by the action of a concentrated solution of potash, but the 

 cells disappear after four or five hours ; even after the application 

 of sulphuric acid, the elastic fibres remain almost unchanged, while 

 the cells are found to have disappeared after six or eight hours 5 

 action, and on the repeated addition of water. 



On boiling these cartilages in water, Donders obtained only a 

 little chondrin, and as elastic tissue generally is not gelatinous, he 

 referred this chondrin to the metamorphosis of the cells, the more 

 especially because he found that after these cartilages had been 

 boiled for five or more hours no cells could be any longer dis- 

 covered by the microscope. Hoppe, on the other hand, considers 

 that during the process of boiling, the cartilage-cells in part escape 

 from the elastic tissue, while the residual tissue so completely sur- 

 rounds the cells that are retained, that they can only be recognised 

 by the aid of a compressor. He is further of opinion that, pos- 

 sibly, Donders might not have sought in the fluid for unchanged 

 cartilage-cells, and that he could not see them in the contracted 

 tissue without using a compressor. 



The present does not appear a fitting place to enter into a 

 consideration of the different forms and groupings of the cartilage- 

 cells or cavities, of their scattered occurrence or arrangement in 

 rows, of the endogenous formations of parent and secondary cells of 

 the first and second generations, &c. ; although all these relations 

 could obviously not exist without simultaneous differences in the 

 chemical substrata. Our chemical knowledge is, however, still 

 too defective to admit of our hazarding any conjecture in reference 

 to the methods by means of which we may hope to ascertain the 

 controlling chemical relations. 



Mulder and Donders saw the morphological elements of true 

 cartilage disappear into very fine granules when exposed under 



