BY JOHN THOMSON, M.B. 36 



educational developinent which has given us our present perfect 

 colour perceptions : — 



1st stage. — The ability to distinguish red from black. 

 2nd stage. — The recognition of the sense of colour apart 



from the sense of light ; the reds, oranges, and 



yellows being apparent. 

 3rd stage. — The perception of green, with its varieties. 

 4th stage. — The detection of blue. 



In connection with red, its recognition in the first stage 

 may be due to its being the most brilliant of the colours. It is 

 certainly the colour manufacturers recognise as preferred by 

 uncivilised races in their desire for something pronounced. It is 

 the colour early acquired by the primitive painter in his art, and 

 in the costume of potentates it survives as the choice for spec- 

 tacular effects of their long departed predecessors. 



To the second stage are referred the Homeric poems and 

 the earlier books of the Old Testament. [See Appendix I.] 



The third stage is not further referred to ; but it is stated 

 of the fourth " that it is not even now reached universally, for 

 in Burmah a striking confusion between green and blue is a 

 perfectly common phenomenon, and a like confusion is some- 

 times observable among ourselves as to these two colours when 

 seen by candle-light." 



Dr. Edridge Green has recently introduced another theory 

 of the evolution of the colour sense. He starts like Magnus 

 believing in the colour-blindness of the primeval man, but he 

 takes a different view of the order in which the perception of 

 colour is acquired. According to Magnus the evolution was in 

 the order of refrangibility ; according to Edridge Green the 

 extremes of the spectrum are first perceived. He quotes very 

 largely from Gladstone's article f See Appendix I.J and seems 

 to build hi3 fancy on Gladstone's finding that Homer was 

 possibly a dichromic, seeing red and violet, and on a patient 

 who colour-blind in one eye saw with it " the two ends of the 

 spectrum tinged with colour and the remainder grey." He 

 believes in a hexachromic theory apparently, because in the 

 normal colour-sighted " six definite points of difference (colour) 

 are distinguished in the spectrum." He expresses his disbelief 

 in the trichromic theory " in the sense that there are three 

 fundamental sensations which are capable of acting indepen- 

 dently of each other." Those who see seven or six colours in the 

 spectrum he calls hexachromic ; five, pentachromic ; four, 



