OF CARTILAGE. 25 
the cartilage is about to become, but is not as yet, ossified), and 
placed under the compressorium, 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 shghtly 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 ITI, fig. 
2, exhibits a portion of cartilage so treated with acetic acid ; 
it is taken from the as yet unossified 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 
