114 THE CONNECTIVE TISSUES, BY A. ROLLETT. 



cartilage. Phenomena of growth of the latter kind are, as we 

 shall hereafter see, to be very beautifully observed in ossifying 

 cartilage. Whether a deposition of new cartilage on the old 

 is effected by the perichondrium, as some authors suppose, 

 is a matter still requiring further observation. Very recently 

 attention has been drawn by Bubnoff to the fact that cartilage 

 is traversed by vessels, the tunica adventitia of which some- 

 times undergoes conversion into cartilage. The relations of the 

 walls of the canals traversing cartilage in which vessels run, to 

 the process of growth, it is therefore obvious, also require 

 investigation. 



In their early stages of development, reticulated cartilages 

 are hyaline, and they retain this condition up to the third or 

 fourth month of foetal life. Fibres make their appearance 

 about the fifth month. Here, as in the elastic fibres of connec- 

 tive tissue, the formation of the fibres can only be traced back 

 to a deposit of fine fibres in the matrix * 



CALCIFIED CARTILAGE. A deposit of the salts of lime fre- 

 quently occurs in the matrix of hyaline cartilage. 



We shall hereafter trace more carefully such calcification of 

 true cartilage in the embryonic cartilaginous skeleton, as a pre- 

 paratory stage of intracartilaginous ossification. Calcification 

 of true cartilage also occurs, in which the calcified tissue per- 

 sists throughout life. Such cartilage was first described with 

 accuracy by J. Muller,-f- in the cortex of the skeleton of the 

 plagiostome fishes, under the name of tesselated calcified 

 cartilage. 



Calcified cartilage occurs also, as was shown by H. Mul- 

 ler,J in a persistent condition at the limits of ossification 

 of the embryonic skeletal cartilage, as, for instance, subja- 

 cent to the articular cartilages, at the junction of the ribs 

 with the cartilages of the ribs, and at the synchondroses of the 



* Rathke, loc. cit. Rabl-Riickhardt, Reichert and Du BoU' Archiv, 1863, 

 p. 41. 



+ Pofrgendorf s Annalen, 1836, p. 347. 



| Zeitschrift fiir wissenschaftliche Zoologte, Band ix., p. 51. 



