340 PHYSIOLOGY. 



tion and thus retard growth and development. In Europe 

 a few years ago the examinations for military service 

 revealed the fact that the stature of the young men 

 was decreasing, and in order to secure the required num- 

 ber of recruits it was necessary to lower the standard. 

 Official investigation was made to ascertain the cause, 

 and experts reported that it was largely due to the use of 

 alcohol. 



Sprains and Dislocations. Sprains and dislocations 

 are injuries to the joints, and often bring more serious 

 results than a broken bone. There should, usually, be 

 complete rest until the part can be used without pain. 

 Otherwise a stiffened joint may result. Hot water applied 

 to a sprain or bruise promotes circulation and prevents dis- 

 coloration. But if there is inflammation cold water should 

 be applied. Bandages may be needed for support. 



Summary. I . The skeleton consists of the axial and appendicular 

 portions. 



2. Each vertebra consists of a body, ring (around spinal cord) and 

 processes. 



3. Pads of cartilage connect the vertebrae. 



4. Bone is traversed by tubes and crevices through which it receives 

 its nourishment from the blood. 



5. Bone consists of animal matter with limy matter embedded in it. 



6. Sprains should be treated carefully to avoid stiffened joints. 



Questions. i . Why do the bones of old people break so much more 

 easily than those of children ? 



2. What is the use of the central marrow ? 



3. What is the work of the red marrow in the spongy ends of the 

 bones ? 



4. What are " sesamoid " bones ? 



