ORGANIZATION. ot 
former in having the intercellular spaces or meshes filled 
with phosphate of lime and other earths, instead of a hya- 
line substance. It may be called petrified cartilage—the 
quantity of earthy matter, and therefore the brittleness of 
the bone, increasing with the age of the animal. If a 
chicken-bone be left in 
dilute muriatic acid sev- 
eral days, it may be tied 
into a knot, since the 
acid has dissolved the 
lime, leaving nothing 
but cartilage and con- 
nective tissue. If a bone 
be burned, it becomes 
light, porous, and _brit- 
tle, the lime alone re- 
maining.” 
Bone is a very vascu- 
Fria. 7.—Transverse section of a Bone (Human 
Femur), X 50, showing Haversian canals. 
lar tissue, that is, it is traversed by minute blood-vessels 
and nerves, which pass through a net-work of tubes, called 
Fig. 8.—Frontal Bone of Human Skull under the 
microscope, showing lacune and canaliculi. 
Haversian canals. The 
canals average yoyo Of 
an inch, being finest 
near the surface of the 
bone, and larger further 
in, where they form a 
cancellated or spongy 
structure, and finally 
merge (in the long 
bones) into the central 
cavity, containing the 
marrow. Under the 
microscope, each canal 
appears to be the cen- 
tre of a multitude of amine, or plates, arranged around it. 
