COMPOSITION OF BONES. lll 
monstrous production, in organs which de not produce it 
in a state of health, as the bram, the heart, and the pla- 
centa *, 
The ordinary colour of bone is white. This, however, 
is usually mixed with other colours in the teeth of herbivo- 
rous quadrupeds. The bones of some varieties of the com- 
mon fowl! approach to blackness, and in some fishes they 
are tinged with green. The nature of the food exercises a 
considerable mfluence over the colour, as demonstrated by 
the red tint which the bones of fowls acquire, when mad- 
der is mixed with their food. 
The texture of bones exhibits many remarkable varic- 
ties. It is compact in some places, as the teeth and bones 
of the ear,—fibrous as the benes of the head in a foetus,— 
or cellular as those of the head of the cetacea. In bones, 
there are likewise tortuous holes, termed sinuses, differing 
from those containing the bloodvessels or marrow, and 
communicating, more or less, directly with the exterior of 
the body. 
The surface of particular bones is irregular, presenting 
eminences which are termed processes, (apophyses.) When 
these processes are united to the bone by the intervention 
-of cartilage, which, with age, becomes ossified, they are 
termed Epiphyses. 
As intimately connected with bone, we may here take 
notice of Cartilage. 'This can scarcely be said to differ in 
its nature, from the cartilaginous basis of the bone. It is 
of a fine fibrous structure, smooth on the surface, and _ re- 
markably elastic. It covers those parts of bones which are 
exposed to friction, as the joints, and is thickest at the 
point of greatest pressure. By its smoothness, it facili- 
tates the motion of the joints, and its elasticity prevents the 
bad. effects of any violent concussion. It is intimately 

* Mownro’s Outlines of Anatomy, p. 62. 
