1910.] 



Light Perce2')tioii to Colour Perception. 



465 

 « 



Case. 



M 



ouocliromatie 

 patches. 



Remarks. 





No. 



X. 







1 



1 



2 



665 

 498 

 429 



167 

 69 



Patch of greatest himinosity, A 571 — 608. 

 Neutral patcli, A. 4854— 5078. 



2 



1 



2 

 3 

 4 



635 

 503 

 494 

 482 

 415 



9 

 12 

 67 



Neutral patch, A 4975—5100. 



3 



1 



2 

 3 

 4 

 5 

 6 



735 

 605 

 534 

 499 

 492 

 482 

 414 



130 

 71 

 35 

 7 

 10 

 68 



Neutral patch, A 5005— 5185. 



4 



1 

 2 

 3 

 4 

 5 

 fl 

 7 



775 

 653 

 517 

 506 

 494 

 484 

 473 

 416 



122 

 136 

 11 

 12 

 10 

 11 

 57 



Patch of greatest luminosity, A 587 — 642. 

 Largest neutral patch, A 504 — 515. 



No defect of light or shade percej)tion. 

 I agreed vpith all his selecti%fis. 



can only perceive a limited number of variations in the spectrum being- 

 entirely ignored. The same argument would, however, apply to a two- 

 colour theory, since we can make innumerable variations with only two 

 variables. A more important argument, however, against the three-colour 

 theory is to be found in the fact that there is a whole group of cases which 

 possess three definite colour sensations and yet are undoubtedly colour-blind. 

 These I have called the class of trichromics. Such persons may match the 

 Holmgren wools perfectly, though they may make mistakes in naming single 

 wools. A very frequent mistake when shown a single skein of yellow wool is 

 to call it red or green, while a blue wool they will call green or violet. 

 Similar mistakes are made with a lantern. When examined with the si^ectro- 

 meter, they will name only three colours as against the six named by an 

 ordinary individual. When questioned, they regard the application of a 

 special name of yellow or blue to definite parts of the spectrum as word- 

 splitting, and would regard the words reddish-green or greenish-violet as 

 more appropriate to the parts of the spectrum in question. 



I give below the details of three trichromic cases as examined by tlie 

 spectrometer. 



