ON THE STRUCTURE OF HYALINE CARTILAGE. 21 



a wide space, unoccupied by cartilage-substance, is enclosed 

 by them. The edges of this space are formed by the appo- 

 sition of the edges of the concavities, but although in close 

 apposition the two layers remain anatomically distinct. In sec- 

 tions treated by silver white tracts connecting the spaces, such 

 as are represented in Figs. 10 and 11, or as have been shown by 

 Heitzmann,can beobtained, and areindicative of the continuity 

 of the cell-covered membrane that forms the free surface of 

 the concavities and the intervening flat surface. As can be 

 easily shown for the cornea, so is it equally true but more 

 difficult to show for cartilage, that the cell-spaces are nothing . 

 more than the separation from each other of distinct laminae. 

 Positive evidence of this can be found in potash preparations, 

 but it is also supported by silver prej)arations, and by the 

 result of such a treatment by osmic acid as is represented in 

 Fig. 13. A white space in a brown ground, as seen in silver 

 preparations of connective tissue, depends upon the fact that 

 the thickness of a space from one epithelium (endothelium) 

 to the other of the two membranes whose separation produces 

 it is sufficient to prevent the dark ground-substance coming 

 into focus. Where the cell-covered membranes are in closer 

 apposition it is impossible to obtain a focus that does not 

 include the dark ground-substance that is above or below the 

 layer of cells. Consequently the unstained thin layer is 

 optically lost in the stained tissue. No tissue is better suited 

 to work this out practically than a well-silvered cornea studied 

 under a good immersion-lens. 



The ordinary granular protoplasmic cells of hyaline carti- 

 lage are analogous, according to the views of the author, to 

 the stellate cells of the cornea and connective tissue gener- 

 ally. In osmic-acid preparations, and in sections soaked 

 in solution of logwood and alum and subsequently treated 

 by acetic acid, when the protoplasma of the cell had shrunk 

 round the nucleus in the centre of the space, he has seen 

 fine glistening fibres enter the cartilage-substance, into which, 

 however, he has not been able to follow them. Such prepa- 

 rations have not been drawn, because it is believed that pre- 

 parations of a more demonstrative nature may yet be obtained, 

 and because none of them have been so conclusive as the 

 results of maceration in blood-serum shown in Fig. 20. 

 That only one process has been traced for each cell in such 

 a preparation is due to a law that seems to hold good for 

 stellate cells in other tissues, and especially in those of bone, 

 that although there are many fibres given off the fibres which 

 are continuous with the long axis of the cell are not unfre- 

 quently, more developed than those which spring from its 



