85 
1921-22.] New Method of investigating Colour Blindness. 
colours, he called green “ yellow,” red “ orange yellow,” violet “ blue,” 
yellow “yellow with faint tinge of green,” red “orange.” The number 
of patches in the diagram, 72, is quite up to normal. There are, however, 
only four steps on the red-green side, but the very high number of five 
steps from peacock-blue to green. There is no doubt whatever this observer 
would fail in the Board of Trade examination, bnt he cannot be called 
colour blind. He is a very striking case of colour difference. The rapid 
change in colour sensation which the normal have in passing along the 
spectrum at yellow is in his case displaced into green. 
8. The woman student who made the lowest mark in the microscope test. Was 
sure there was nothing abnormal about her colour vision, but, as diagram 
shows, she is below the average. Passed bead test with ease. 48 patches. 
9. No. 585 in microscope test. Did not think there was anything the matter with 
his colour vision. Differed with a relative about colour of a cloth, but 
attached no importance to difference. In the bead test put peacock-blue 
into green, and hesitated extremely long over ultramarine before putting it 
into blue, but otherwise there was nothing remarkable. His case is a 
striking one, as the number of patches is so low, only 14 ; but he was quite 
certain the steps were not too large. It will be noticed, however, that the 
diagram here is not distorted in any way, but that the observer is equally 
weak all over ; it is distortion rather than weakness that causes the observer 
to mistake the colours. 
10. No. 38 of perception spectrometer test. The sky was very dark when the test 
was made — not dark enough, however, to require the use of artificial light 
indoors. More patches would probably have been obtained under ordinary 
conditions. Was slow at bead test, but made no errors. 8 patches. 
11. No. 200 of the microscope test. Failed altogether to distinguish red from 
green by that test. Thought Vandyke-brown a perfect match for the red 
and blue of the Union Jack. My worst case. He made all the readings 
of the new test in a confident manner, and I found it impossible to 
confuse him into recognising changes of intensity for changes of colour. 
9 patches. 
12. This observer knew he was colour blind, but did not consider his case a bad one. 
In bead test put red into green, and pink into blue. His case brought 
to my notice through his being unable to do a methyl-orange titration. 
11 patches. 
13. Had difficulty with methyl-orange titration, and came to see how bad his colour 
vision was. In bead test put green and peacock-blue into red, and pink 
into blue. When shown spectrum colours, called orange, yellowish green, 
and green all “ yellow,” greenish blue a “ bluey white.” 12 patches. 
14. Confused green and yellow when examined with the lantern for the R.A.F., 
but was passed. Came as a result of a difficulty with perimeter test in 
Physiology Department. In bead test put greenish yellow in green, and 
pale pink and dark pink in blue. 17 patches. 
15. No. 554 in microscope test. Knew he was colour blind, as he had been rejected 
