COLOR BLINDNESS 141 



respond, the green nerve fibers alone being stimulated, and 

 the brain therefore interprets green. 



A well-known author gives an amusing incident of a dinner 

 party, at which the host offered stewed tomato for apple 

 sauce. What color nerves were defective in the case of the 

 host ? 



In some employments color blindness in an employee would 

 be fatal to many lives. Engineers and pilots govern the di- 

 rection and speed of trains and boats largely by the colored 

 signals which flash out in the night's darkness or move in the 

 day's bright light, and any mistake in the reading of color 

 signals would imperil the lives of travelers. For this reason 

 a rigid test in color is given to all persons seeking such em- 

 ployment, and the ability to match ribbons and yarns of all 

 ordinary hues is an unvarying requirement for efficiency. 



