4 8 CARTILAGE-TISSUE. [sect. 24. 



them to elastic tissue. On the other hand, the cartilage-capsules, 

 or the secondary membranes of the cartilage-cells, appear to pass 

 gradually into a gelatiniferous substance, as may be concluded 

 from their becoming more or less altered on boiling, and particu- 

 larly from the capsules of the mother-cells, which are more or less 

 blended with the matrix, being dissolved by boiling. The contents 

 of the cells coagulate in water and in dilute organic acids, and rea- 

 dily dissolve in alkalies. The matrix, in the majority of cartilages, 

 yields chondrm; and it is only in reticular cartilages that it is 

 composed of a material very nearly related to the substance of 

 elastic tissue. Accordingly, the cartilages which consist only of 

 cartilage-cells, and reticular cartilage, yield, on boiling in water 

 little or no gelatine, and the presence of that substance is not 

 characteristic of cartilage-tissue. 



In a physiological point of view, the firmness and elasticity of 

 cartilage is especially to be noticed, properties by which the carti- 

 lages are of use in various ways. In growing cartilages, the nutri- 

 tive change is very energetic, and in certain places they always 

 contain numerous blood-vessels, in special canals, and, as I have 

 shown in the septum ?iasi of the calf, even nerves. The cartilages 

 are developed from the primitive embryonal cell- masses; the cells 

 of the latter becoming converted into cartilage-cells, and, at least 

 m many cases, a homogeneous intercellular substance appearing 

 between them, which is derived from transuded constituents of 

 the blood. The growth of cartilage is effected, firstly, by endoge- 

 nous cell-multiplication, traces of which are always discernible 

 even in fully-formed cartilage; and, secondly, by the deposition of 

 an intermediate substance from the blood-plasma, between the 

 cells, which m every case at first solely constitute the cartilage 

 The intermediate substance, according to Schiwnn's observations 

 yields at first no chondrin, even in the true cartilages, and subse- 

 quently increases more and more in quantity. A growth of carti- 

 lage, by the apposition of new layers outside the part of the carti- 

 lage already formed, as Gerlach assumes, has been nowhere proved 

 with certainty. In fully developed cartilage, the change of mate- 

 rial is certainly not energetic; and, apart from the vessels of the 

 perichondrium coveriug many cartilages, and those of the adjoin- 

 ing bone, no special means are provided for effecting such change 

 except m the cartilages of some mammals (septum of the nose) 

 and of the Plagiostoma ; in which latter, according to Leydig even 

 m old animals, there occur vascular canals (ray), or anastomosing 

 fusiform, or stellate cartilage-cells (shark, chimera, acipenser) 



