OF CARTILAGE. 25 



the cartilage is about to become, but is not as yet, ossified), and 

 placed under the compressorinm, the cells will be seen to lie so 

 closely in it, that the space occupied by them may be estimated 

 at three fourths, and that of the intercellular substance at one 

 fourth of the whole volume. Many of the cells which have 

 become separated by the process of cutting, float already in the 

 fluid; and on slightly compressing the preparation many more 

 become loose, and flow out in streams from the intercellular 

 substance into the surrounding fluid. The intercellular sub- 

 stance is too soft to prevent the separation, but at a subsequent 

 period of development this cannot be effected. According to 

 Meckauer the cartilage-corpuscles may also be isolated by boil- 

 ing. I once succeeded in crushing one of these young carti- 

 lage-cells while still in connexion with the preparation. The 

 first effect of the compressorium was to produce an extension 

 of breadth ; it then suddenly shrank together, whilst a clear 

 fluid streamed out, thus proving the contents of the cell to be 

 fluid and transparent. Now, inasmuch as these cells present in 

 different instances a more or less granulous appearance, it fol- 

 lows that the cells of ossifying cartilage must have a peculiar 

 investing membrane, which is granulous, and thus that they 

 are actual elementary cells, in our sense of the word, and nei- 

 ther mere excavations in the substance, nor perfectly solid 

 corpuscles. The appearance of the cells which float about en- 

 tirely accords also with this view, for while their contents seem 

 to be clear, the cells look granulated. All of them contain a very 

 beautiful oval or circular, not flattened cell-nucleus, situate 

 upon the internal surface of the wall, and this nucleus en- 

 closes one or two very distinct nucleoli ; in short, they in every 

 respect accord with the elementary cells of most of the other 

 tissues. By the aid of acetic acid we may also frequently suc- 

 ceed in rendering the cell-walls visible upon a thin lamella of 

 cartilage, and as the cell-contents are at the same time dis- 

 solved by the acid, it has the additional advantage of bringing 

 the nucleus into view, which is sometimes indistinct in conse- 

 quence of the granulous nature of the contents. Plate III, fig. 

 2, exhibits a portion of cartilage so treated with acetic acid ; 

 it is taken from the as yet unossificd portion of the ilium of an 

 embryo pig of five inches in length. The cell- walls, with their 

 double outlines, may be seen, and both the illuminated and 



D. KL HILL UBRARY 



