230 THE NERVOUS SYSTEM OF MAN 



cipals is that they can usually tell a cigarette boy by his 

 general attitude, poor scholarship, and disregard of per- 

 sonal appearance. 



When cigarettes are burned, three distinct poisons are 

 produced, which cause serious effects on the boys who use 

 tobacco in this form. These poisons are absorbed in small 

 quantities by the mucous membrane which lines the nasal 

 passages and in larger quantities when the smoke is in- 

 haled in the lungs. 



A simple way to prove that cigarette smoke contains a 

 poison is by blowing the smoke through a glass tube into 

 an aquarium containing goldfish. Only a small amount 

 of smoke w r ill kill the fish. 



While we can all gradually adapt ourselves to small 

 amounts of poison, poisons are never beneficial unless pre- 

 scribed by a physician to try to remedy some bodily defect. 

 The poisons which arise from the burning of a cigarette 

 are never prescribed even as medicines, and have never 

 been found in any way beneficial to the human body. 



SUMMARY 



The nervous system of all vertebrates consists of a brain 

 and spinal cord with nerves passing to all organs of the 

 body. The brain of man is the most highly developed. 



All our movements are controlled by means of the nerv- 

 ous system. Through our sense organs we gain our 

 information of the world. 



The nervous system is made up of cells which are 

 highly specialized. Their main work is to transmit and 

 interpret stimuli. The nerves of man are so highly spe- 

 cialized that all stimuli which affect the eye are thought 

 1 > v us to be light stimuli ; or all stimuli which enter in 

 the ear, seem to be sounds. The information which passes 

 over any of our special sense organs travels over several 



