110 



Colour Adaptation. 

 By F. W. Edridge-Gkeen, M.D., F.E.C.S., Beit Memorial Besearch Bellow. 



(Communicated by Prof. E. H. Starling, F.R.S. Received October 4, 1912, — 



Bead January 23, 1913.) 



(From the Institute of Physiology, University College, London.) 



As in dark adaptation there is a considerable effect which takes place 

 immediately on entering a dark room, but which increases with the length of 

 stay and the degree of darkness, so is there a considerable effect produced 

 when a person enters a room illuminated by an artificial light, having 

 previously been in daylight. This effect, whicb may be designated colour 

 adaptation, increases with the time during which the eyes are subjected to 

 the adapting light. I have estimated the effect of colour adaptation in four 

 ways. 



I. A dark room being illuminated by light of a certain wave-length, one 

 eye is subjected to light of this wave-length whilst the otber is closed, and is 

 therefore in a state of more or less dark adaptation. The dark room com- 

 municates with another dark room by a door in which a hole is pierced to 

 allow the passage of the eyepiece of my spectrometer.* A certain region 

 of the spectrum is isolated by my spectrometer ; and, after the stated 

 period, this is examined first by the eye which has been exposed to the 

 light, and then with the eye which has been covered up. The same 

 spectral region is also observed after both eyes have been subjected to the 

 adapting light. 



II. The second method consists of wearing a pair of spectacles glazed with 

 coloured glass, and noticing the changes which appear in coloured objects 

 viewed through these glasses for a longer or shorter period. No light is 

 allowed to enter the eye, except through the coloured glasses. As the com- 

 position of the light which passes through the glasses is known, those changes 

 which are clue to the absorption of light by the coloured glass can be separated 

 from those which cannot be accounted for in this way. Definite spectral 

 regions are examined first immediately after putting on the glasses, and then 

 again after a longer period. 



III. The third method is to note the changes which appear in coloured 

 objects in a room illuminated by light of known composition, which cannot 

 be explained by the character of the light. 



* ' Eoy. Soc. Proc.,' 1910, B, vol. 82, p. 458 ; ' Hunterian Lectures on Colour Vision 

 and Colour Blindness,' p. 73, Kegan, Paul & Co. 



