362 APPLIED PHYSIOLOGY 



in the same way as man. A bird's wing is bone for bone almost like a 

 man's arm and hand. A turtle's shell is its ribs, while- the bones of its 

 limbs are like those of man. 



SUMMARY 



1. About 200 bones give the body form and strength. 



2. The outside of all bone is a hard plate, while the inside 



is either a fine network of bone or else is hollow. 

 3.- The hollow form of bone combines strength with light- 

 ness. 



4. Bone is composed of living cells and fibers nourished 



by arteries and endowed with sensibility by nerves. 

 Lime is mixed with the cells like starch with linen. 



5. Bone is covered with a tough membrane called theferi- 



osteum, which carries the blood tubes and nerves to 

 the bone, and forms new bone during the period of 

 growth or when the bone is diseased. 



6. Cells and fibers resembling those in bone, but contain- 



ing no lime, form cartilage. 



DEMONSTRATIONS 



156. Show a complete skeleton of at least a small animal. Point 

 out the different shapes of the bones and how they are adapted to their 

 positions and work. Point out in the living body where the different 

 bones can be felt. 



157. Procure a fresh beef bone, and another similar one dried. Note 

 the bright pink color of the fresh bone, and the white or brown color 

 of the dried specimen. Notice that the periosteum can be stripped 

 from the bone. Notice the soft cartilage which covers the ends of the 

 bone. 



158. Saw a long bone in two crosswise and then saw one half in two 

 lengthwise. Notice the hollow cavity in the shaft of the bone and the 

 fat or marrow which fills it. Notice the honeycombed appearance of 

 the inside of the ends of the bone. 



159. Procure a specimen of bone mounted for the microscope. 

 Using a power of at least fifty diameters., notice the circles of bone cells 



