388 SCIENCE PROGRESS 



brain we may ascribe it to excessive disturbance of the vibrators 

 in the retina. This would make the energy curves widen out 

 and lose their distinctive form. 



The colour of the sensation produced by monochromatic 

 stimulation varies with the intensity of the latter, becoming 

 whiter for high intensities. This follows naturally from the 

 theory developed here ; when the amplitude of the vibrators 

 is increased, they will be subject to more disturbance, and 

 their motion will consequently be more irregular. Hence its 

 energy will be more widely distributed over the spectrum. 



