

PARENCHYMATOUS OR CELLULAR CARTILAGE. 109 



and to others based on comparative anatomy, and thus allude, 

 for instance, to the early stages of cartilage, to the primordial 

 cells of cartilage and the tissues composed of them. 



In order, however, to diagnose the cells as cartilage cells, of 

 whose history and development we have no information, it is 

 requisite that We should be better acquainted with their inter- 

 nal organization than at present, as well as with the differences 

 that exist between cartilage cells and other masses of proto- 

 plasm. Other difficulties similar to those that are here met with 

 in regard to the limitation of the cartilaginous tissue, frequently 

 arise when the identification of cells is under consideration. 

 Experiments undertaken to determine whether in the cells con- 

 tained in the Tendo Achillis, and in the digital tendons of the 

 Frog or Triton, similar phenomena follow the application of 

 induction shocks to those observed in the cells of the hyaline 

 cartilages of these animals, have altogether failed. 



DEVELOPMENT OF CARTILAGE. Hyaline cartilage exhibits 

 in most instances an unmistakable similarity to the first 

 rudiments of all animal tissues, in being composed of cells 

 advanced to a nearly equal grade of development. 



The investigations of Rathke* on chickens, and of Kollikerf" 

 on tadpoles, have taught us that the embryonic cells whilst still 

 filled with yolk granules, as they gradually increase, become 

 more transparent ; and then becoming separated from each other 

 in consequence of the development of rods of a homogeneous 

 and transparent substance, finally constitute the first rudiments 

 of embryonic cartilage. 



As soon as the matrix has become distinctly differentiated 

 from the previously closely compressed cells, it forms a homo- 

 geneous clear ring around each, and between these rings run 

 fine lines resembling the contour lines of epithelial cells. At 

 this period, therefore, the cartilage consists of cells which are 

 contained in polyhedric capsules, and no special artifice is re- 

 quired in order to isolate the cells completely, together with their 

 capsules. The costal cartilages of young sheep, or of human 



* Froriep and Schleiden's Notizen, Band ii., 1847, p. 305. 

 f Mikroskopische Anatomic, Band ii., p. 349. 



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