STUDIES IN SPECIAL SENSE PHYSIOLOGY 415 



red and blue to his flesh tints, and Rubens contrasted a bright 

 red with his " still cooler flesh colour " (Eastlake). 1 



The point to mark is the general agreement that certain of our 

 sensations of colour are really singled out from the whole group 

 as presenting sharply-defined, special characters. All sensational 

 theories are primarily concerned with the definition of these char- 

 acters, and secondarily with an attempt to describe the data in 

 terms of a physiological hypothesis. 



Of such attempts the views developed by Professor Ewald 

 Hering and his pupils during the last five-and-thirty years are the 

 most valuable results. Whatever may be our ultimate conclusion 

 as to the validity of these theories, no one can doubt that they have 

 greatly advanced our knowledge of visual physiology, and their 

 study cannot be neglected by any one desirous of acquiring even a 

 superficial idea of modern conceptions. 



According to Bering's method of analysis our whole visual world 

 can be resolved into six elementary sensation qualities white, 

 black, the toneless, and blue, yellow, green, red, the toned or 

 bright (bunte) colours. 



If we consider the tone-free qualities, we can form a series of 

 shades or graduations passing from intensest white to deepest 

 black. If we attend to the toned colours, they can be arranged 

 in a circle with four divisions. 



" If we choose in such a cdour circle any colour as starting- 

 point, for instance a red similar to that with which a spectrum 

 usually begins at the long-waved end, we see the red colours 

 arranged in one direction gradually becoming more yellowish, while 

 the redness of the colours correspondingly diminishes, until finally, 

 passing through orange and golden-yellow, we arrive at a yellow 

 which contains no trace of the red which is still so apparent in 

 the orange. To this yellow succeed other yellow colours which 

 play more and more into the green (sulphur-yellow, canary-yellow) ; 

 further on (as in sap-green) the yellowishness recedes more and 



1 In the work of Rembrandt, who is, I believe, regarded by those qualified to 

 judge as the greatest exponent of contrastive effects, the most striking results seem to 

 be rather light-dark contrasts, as in the Hague " Anatomic," than 8]>ecific colour 

 op]Nisitiinis. Fur instance, in the (so-culled) ' Nachtwache, " the yellow sunlight and 

 yellow c..stunif of one of the central figures, which produce such a magnificent 

 brightening effect, are balanced by general shadow without any apparent uso of the 

 " Gegenfarbe." This seems to apply also to the " Staalmeesters." A careful study 

 <>t the chief master- works of painting from the stand) mint of the visual physiologist 

 would IK- most interesting. 



