126 
MESSRS. J. TOMES AND C. DE MORGAN ON THE 
We have traced in temporary cartilage those changes which occur preparatory to 
its conversion into bone : it now remains for the authors to describe the results ot 
their researches on the mode in which that conversion is effected, and concerning 
which there hitherto has been a great diversity of opinion. 
Preceding ossific deposit, the intercolumnar tissue, which may not only be seen 
between the columns of cells, but also passing more or less perfectly between the 
individual cells, becomes in some cases slightly fibrous in appearance, and of a light 
brown colour ; this condition speedily gives way to a highly granular state ; in fact it 
has become bone, and encloses, in osseous cavities or crypts, the cartilage cells. For 
reasons which will hereafter be sufficiently obvious, we shall in future call these 
lacunal cells. If thin sections be made with a very sharp knife through ossifying 
cartilage, and placed in water or albumen under the quarter or eighth object-glass, 
we shall occasionally find lacunal cells which have escaped from their osseous crypts, 
floating loose in the fluid, and offering a favourable opportunity for the examination 
of their characters. It may then be seen that the thick pellucid outer investment 
has become granular, and that the enclosed granular cell has lost its regular outline, 
and become angular or ragged, while the nucleus has become obscured by the changes 
in the more external parts of the cell, an early stage of which is seen in Plate VIII. 
fig. 19 and 22 a. Such are the appearances presented in some of the detached 
lacunal cells, but they may be seen in both earlier and later stages of development 
than that described. Thus instances may be found where the outer coat has only a 
few granules on the surface, in which case the granular cell may be seen more di- 
stinctly, and minute elongated processes traced, extending from its surface (Plate 
VIII. figs. 19 and 20). In a favourable section we sometimes find such a cell with 
its outer coat torn, exposing to full view the granular cell, with numerous and well- 
marked processes extending from it. Dr. Sharpey kindly placed at the disposal of 
the authors the rickety bone of a child who died during the active condition of the 
disease. In this specimen granular cells with radiating processes can with great 
readiness be detached by tearing a thin section, for in this case cartilage assumed 
the arrangement of bone without the impregnation of earthy ingredients (Plate VIII. 
fig. 23)*. 
The third condition, in which we may find isolated lacunal cells detached from 
the osseous crypts of the intercellular tissue, differs from those already described in 
their greater solidity. The whole mass has become highly granular, and the granular 
cell with its processes has united to the outer coat, so that the two can no longer be 
* Kollikek, oper. cit. at p. 360, describes accurately the formation of lacunse from cartilage cells in a rickety 
bone, and although he has not observed the changes with equal distinctness in normal bone, appears to have 
satisfied himself that in the ossification of cartilage the cells of the latter become converted into lacuna. 
M. Kolliker does not however seem to have recognized the relation of the lacunal cells as such to the inter- 
cellular tissue, neither does he mention the fact that the granular cells with their long stellated processes can 
be separated from the investing cell- wall in the manner described in the text. 
