ORGANIZATION. 
37 
Fig. 7. —Transverse section of a Bone (Human 
Femur), X 50, showing Haversian canals. 
age of the animal. If a chicken-bone be left in dilute 
muriatic acid several days, it may be tied into a knot, since 
the acid has dissolved 
the lime, leaving noth¬ 
ing but cartilage and 
connective tissue. If a 
bone be burned, it be¬ 
comes light, porous, and 
brittle, the lime alone 
remaining. 15 
Bone is a very vas¬ 
cular tissue; that is, it 
is traversed by minute 
blood-vessels and nerves, 
which pass through a 
net-work of tubes, called Haversian canals . The canals 
average Tjnro of an inch, being finest near the surface of 
the bone, and larger further in, where they form a cancel¬ 
lated 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 
laminae , or plates, ar¬ 
ranged around it. Ly¬ 
ing between these plates 
are little cavities, called 
lacunae , which are con¬ 
nected by exceedingly 
Fig. 8.—Frontal Bone of Human Skull under the fine tubes, Or Canaliculi . 
microscope, showing lacunae and eanaliculi. Thefle represent the 
spaces occupied by the original cells of the bone, and 
differ in shape and size in different animals. 
