OSSIFYING CARTILAGE. 
171 
particles of osseous matter. If such a section be placed 
in dilute acid, these particles alone are removed, and 
the matrix in which they were imbedded presents a 
granular appearance. I have found, that in the crania 
of very small birds, as the Canary , where the bone is 
too thin to admit of bone-cells, the earthy particles are 
not only of large size, but each, as shown by B, in 
Fig. 134, is of a rhombohedral form. In the cartilage 
of the cranium of Rana paradoxa, minute needle- 
shaped crystals somewhat resembling the raphides in 
the Squill and Hyacinth , are occasionally found in the 
interior of each cell, thus proving that ossific matter 
may be deposited either in a granular or crystalline 
form. 
In the cartilage of many fishes, as the Shark, Skate, 
and Saw-fish, the ossific matter is in the form of 
granules, and occurs principally in the neighbourhood of 
the cells ; in the Skate, the 
deposit sometimes takes place 
within the cell wall. To the 
latter I give the name cellu- 
lar, and to the former inter- 
cellular ossification. In Fig, 
132, are shown two portions 
of the cranial cartilage of a 
Skate ; the one represented 
by a, exhibits a mass of cells 
imbedded in a more or less 
structureless matrix, whilst in 
FIG. 132 . 
A 
B 
Cartilage from the cranium of 
a Skate : a, cells imbedded in a 
structureless matrix, b, granules 
of ossific matter around the cells. 
