ORGANIZATION. 



37 



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." 



Bone is a very vas- 

 cular tissue; that is, it 

 is traversed by minute 

 blood-vessels and nerves, „ . „ . „ 



which pass through a Femur), x 50, showiug Haveisian canals. 



net-work of tubes, called Haversian canals. The canals 

 average xsVir 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 

 the 



^^^J>^^ 



cavity, contaming 

 marrow. Under the 

 microscope, each canal 

 appears to be the cen- 

 tre of a multitude of 

 lamince, or plates, ar- 

 ranged around it. Ly- 

 ing between tliese plates- 

 are little cavities, called 

 lacuncB, wliieli are con- 

 nected by exceedingly 



Fto. 8.— Fiiintnl none of Human Skull under the AnetnheS,or CanallCuU. 

 microscope, showing lucuuie ami caualiculi. rpi^^^^ represent the 



spaces occupied by the original cells of the bone, and. 

 diflfer in shape and size in different animals. 



