1890.] on Colour-Vision and Colour-Blindness. 131 



select the greens rapidly and without hesitation, will select nothing 

 else, and will select with a certain readiness and confidence easily 

 recognised by an experienced examiner, and wdiich may even be 

 carried to the extent of neglecting the minute accuracy which a person 

 who distrusts his own colour-sight will frequently endeavour to 

 display. Some normal-sighted peoj^le will complete their selection 

 by taking greens which incline to yellow, and greens which incline to 

 blue, while others will reject both ; but this is a difference depending 

 sometimes upon imperfect colour educati(m, sometimes upon the in- 

 terpretation placed upon the directions of the examiner; for the 

 person who so selects sees the green clement in both the yellow- 

 greens and the blue-greens, and is not colour-blind. The completely 

 colour-blind, whether to red or to green, will proceed with almost as 

 much speed and confidence as the colour-sighted; and will rapidly 

 pick out a number of drabs, fawns, stone-colours, pinks, or yellows. 

 Between the foregoing classes we meet with a few people who declare 

 the imperfection of their colour-sense by the extreme care with which 

 they select, by their slowness, by their hesitation, and by their desire 

 to compare this or that skein with the pattern more narrowly than the 

 conditions of the trial should permit. They may or may not ulti- 

 mately add one or more of the confusion colours to the green, but 

 they have a manifest tendency to do so, and a general uncertainty in 

 their choice. One of the great advantages of Holmgren's method 

 over every other is the way in which the examiner is able to judge, 

 not only by the final choice of matches, but also by the manner in 

 which the choice is made, by the action of the hands, and by the 

 gestures and general deportment of the examinee.- 



When confusion colours have been selected, or when an unnatural 

 slowness and hesitation have been shown in selecting, the examinee 

 must be regarded as either completely or incompletely colour-blind. 

 In order to determine which, and also to which colour he is defective, 

 he is subjected to the second test. For this, the wool is mixed again, 

 and the pattern this time is a skein of light purple — that is, of a 

 mixture of red and violet much diluted with white \sliown\. To match 

 this, the colour-blind always selects deeper colours. If he puts only 

 deeper purples, he is incompletely colour-blind. If he takes blue or 

 violet, either with or without purple, he is completely red-blind. If 

 he takes green or grey, or one alone, with or without purple, he is 

 completely green-blind. If he takes red or orange, with or without 

 purple, he is violet-blind. If there be any doubt, the examinee may 

 be subjected to a third test, which is not necessary for the satisfaction 

 of an expert, but which sometimes strengthens the proof in the eyes 

 of a bystander. The pattern for this third test is a skein of bright 

 red, to be used in the same way as the green and the purple \sliown\. 

 The red-blind selects for this dark greens and browns which are 

 much darker than the pattern ; while the green-blind selects greens 

 and browns which are lighter than the pattern. 



The method of examination thus described is, I believe, absolutely 



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