366 THE ANIMALS AND MAN 



nervous system something, and nothing can take the place 

 of the complete relaxation that comes through sleep. Every 

 child should sleep at least ten hours, and ordinarily every 

 adult at least eight hours each night. Thus only can the 

 brain cells rest and recuperate for the next day's activities. 



Necessity of food and fresh air. — From what we have 

 learned of the function of nerve cells and of metabolism 

 of cells in general, we know that an active nerve cell is 

 constantly using up energy, and is constantly wasting away 

 and being rebuilt. This necessitates a constant supply 

 of nutriment and oxygen. The blood furnishes these to 

 the nerve tissues just as to all other tissues, hence when 

 we are eating proper food and breathing in the fresh air 

 we are satisfying the needs of the nerve tissues as well as 

 those of other parts of the body. 



Effect of alcohol on the nervous system. — In its normal 

 healthy condition, the nervous system is an efficient regulator 

 of the bodily activities. It inhibits or excites the various 

 organs of the body according to their needs. We can 

 readily understand that any substance, which, when taken 

 into the body, interferes with the nervous system as a regula- 

 tor of the body, is a deleterious substance. This is what 

 alcohol does. Chiefly, it paralyses the inhibitory centers 

 so as to weaken or dissipate the control of the nervous 

 system. It causes an abnormal distribution of blood by 

 its action upon certain nerve centers. Dr. D. S. Jordan in 

 the "Popular Science Monthly," Feb. 1898, sums up the 

 effect of alcohol and other stimulants upon the nervous 

 system in these words: 



"The healthy mind stands in clear and normal relations 

 to Nature. It feels pain as pain. It feels action as pleasmre. 

 The drug which conceals pain or gives false pleasure when 

 pleasure does not exist forces a He upon the nervous system. 

 The drug which disposes to reverie rather than to work, 

 which makes us feel well when we are not well, destroys 



