240 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VOL. V. 



light induction or negative contrast. But such an explanation will not 

 suffice. For it is clear that if the spreading of the red stimulation 

 around the small (aperture) surface counteracts to a certain degree the 

 green induction, what we would expect to issue is not blue by any 

 means but colourless light, because it is a case of the counteraction 

 of complementaries (red and green), which of course, would produce 

 colourless light. But even if we suppose that the negative induction is 

 not sufficient in degree to completely counteract the positive induction 

 (green), what we would expect from this is dL green of weakened satura- 

 tion and not under any circumstances blue, as was the case in our 

 experiments. For the influence of the negative contrast would simply 

 be to neutralise the positive colour quality of some of the green induced 

 by the red environs, which would, unless a case of complete counter- 

 action where colourless light is the outcome, leave less green light 

 interfused with much grey light produced by the mutual neutralisation 

 of positive and negative inductions, and this is tantamount to saying 

 the result is a green of poorer saturation instead of blue. So that the 

 question remains over for the Hering theory quite as awkward as ever. 

 Even if we admit the possibility of a gratuitous deviation from that 

 which the theory would lead us to expect and suppose, that in some 

 way or other this negative contrast influence might succeed in produ- 

 cing some other colour result than green, we have yet to explain why it 

 should not as likely be some colour on W^^ yellow side oi green, as one 

 on the blue side. We can find no a priori reason for any presumption 

 that the blue should obtain the favoured lot of this fortuitous birth. It 

 might just as well ho. yellow, and the fact that blue actually obtains is a 

 phenomenon which to our minds has not been and cannot be explained 

 by recourse to negative induction or any such device born of the 

 exigencies of a desperate theory. 



In fact, so far as I can see, Hering's theory makes no provision for 

 any such disturbance in the ordinary complementary relationships of 

 the members of our colour system such as the remarkable colour blind 

 case cited seems to demand, and which our space threshold experiments 

 corroborate as possible not merely for abnormal cases but for the 

 normal eye also at small visual angles.* 



*Also the very ingenious but somewhat complicated theory of Ebinghaus does not give account of these 

 facts and we may suggest that such a case as Prof. A., where the colour blindness was not only monocular, 

 but where the subject was at the same time an expert opticist — a coincidence which will not frequently occur. 

 — such a case should not be disposed of in the summary way in which Ebinghaus treats it in his article. 

 — Zeitschrift fur Psychologie, Band V, Page 215. 



