The Framework of the Body 47 



before maturity may produce a similar effect, hindering 

 the full activity of bone cell-growth and thus preventing 

 full development of the bones. 



Surgeons recognize the fact that the broken bones of 

 drunkards usually unite with greater difficulty than do those 

 of the average patient. The use of alcoholic liquors is also 

 one of the most frequent predisposing causes of the serious 

 and painful disease known as gout, which often attacks the 

 joints. 



71. Effect of Tobacco upon the Bony Tissues. Powerful 

 narcotics, like tobacco and opium, by retarding the activity 

 of bone cell-growth, hinder the building up of the bodily 

 frame. The formation of healthy bone tissue demands 

 good, nutritious blood ; but if this vital tissue is loaded with 

 poisonous narcotics, the bones are defrauded of their proper 

 building material. 



ADDITIONAL EXPERIMENTS 



Experiment 15. To illustrate the movement of torsion in the spine, 

 or its rotation round its own axis. Sit upright, with the back and 

 shoulders well applied against the back of a chair. Note that the 

 head and neck can be turned as far as 60 or 70. Now bend for- 

 ward, so as to let the dorsal and lumbar vertebrae come into play, 

 and the head can be turned 30 more. 



Experiment 16. To show how the spinal vertebra make a firm 

 but flexible column. Take twenty-four hard-rubber overcoat buttons, 

 or the same number of coins, and pile them on top of one another. 

 A thin layer of soft putty may be put between the coins to represent 

 the pads of cartilage between the vertebrae. The most striking 

 features of the spinal column may be illustrated by this simple 

 apparatus. 



NOTE. As the succe'eding chapters are studied, additional experiments 

 on bones and their relation to other parts of the body will readily sug- 

 gest themselves to the ingenious instructor or the thoughtful student. Such 

 experiments may be utilized for review or other exercises. 



