Report of (he Committee on Colour- Vision. 333 



nevertheless, in by far the majority of cases of this sort, as in 

 central amblyopia from tobacco, &c, acuteness of vision is so 

 much lowered as to be for the patient the most important symptom. 

 I remember only one case in which the patient, a sailor, who had 

 been accustomed to steer and to look out, discovered his inability 

 to distinguish the colour of ships' lights, whilst his acuteness of 

 sight still remaiued good enough for ordinary purposes about the 

 ship. (Wm. B. " T.O.P.," iii, 33.) How the loss of colour-vision 

 stands in relation to loss of light perception in cases of optic nerve 

 disease, I cannot say. People suffering from disease of the optic 

 nerves often come saying they want glasses for failing sight, and 

 naturally think the defect can be remedied by glasses. Glasses 

 do not help the matter, though they of course may remedy the 

 form so far as the defect is due to the images not being properly 

 focussed. 



Question — It has been alleged on behalf of railway workers 

 that the seuse of colour-vision becomes impaired after long- 

 hours of work and want of rest ? — I have no evidence on that 

 subject ; but I should not have thought it likely to be true. 



Question — Have you had any experience of hysterical colour- 

 blindness? — Yes, but I have not put together my facts about 

 it. Contraction of field and lowering of acuteness of form-per- 

 ception are nearly constant ; but the state of colour-perception, 

 according to my experience, varies greatly. The fields sometimes 

 show spiral contractions, but not always. The spiral contraction 

 is, as a rule, put down to exhaustion. 



About congenital colour-blindness I have not much to say, 

 except thai it is common in men and very rare in women. I 

 have one splendid case of a colour-blind woman — the only one I 

 have ever seen of the kind. It is not common green-blindness ; 

 I think it must be blue-blindness. She never makes mistakes 

 about green, and is always wrong about other colours. I use 

 Holmgren's test. 



Question — You have had some experience with the use of 

 a lamp ? Can you make any statement about that ? — The results 

 with the lamp vary very much. I cannot quote statistics ; but I 

 think it is true that as a rule people congenitally colour-blind 

 will make fewer mistakes with such a test than those whose 

 colour-defect has come on with disease of the optic nerve, e.g., 

 tobacco cases. But both classes are liable to make mistakes 

 if taken off their guard by varying the colour of the glass, 

 the size of the aperture, or the brightness of illumination. 

 A further cause of variation lies in the interest or attention 

 that the examinee shows ; he may make mistakes at first, but 

 learn to correct them if the tests are repeated. I should not 

 myself, as at present advised, rely upon a lantern-test alone, 

 either as a scientific test of colour defect, or as a trustworthy 

 guide for the detection of those whose colour-defect is dangerous. 

 The wool-test is much less open to these objections, because 

 the number of tints and shades is so much larger, and possibly 



