tgoS.] 



OF SUBLIMINALLY COLORED STIMULI. 377 



The experiments were carried out by means of a simplified form 

 of the Zimmermann perimeter, which permitted an accurate record 

 of the degree of eccentricity at which the stimukis was exposed. 

 Exploration was confined to the horizontal nasal meridian of each 

 eye. The stimulus was a beam of light from an electric (i6 c. p.) 

 lamp, transmitted through appropriate combinations of gelatines and 

 colored glasses; the colors employed were (non-equated) B and Y, 

 R and G. Six of the most reliable laboratory students^" acted as 

 observers, and Professor Baird had personal charge of the entire 

 work. The after-images were projected upon white, gray and black 

 grounds. The experiments proper were preceded by a careful de- 

 termination of the outermost limits of color vision for the stimuli 

 used, and all pains were taken to avoid chromatic adaptation. 



The following may serve as a sample of method and results. 



Determination of Outermost Limits of Blue Vision: Observer Bu. 



Right Eye. 



Outermost limit (bluish or blue) : 48°. 



the peripheral retina in light-adaptation and in dark-adaptation. In the 

 latter case, after-images — both uncolored and colored — are faint or wholly 

 lacking. In the former case they are readily perceptible. Yet even in 

 light-adaptation they are less perceptible than are the primary images 

 aroused by the given stimuli." 



^^ The Misses M. Miller, A.B., and B. Scoggin : and Messrs. C. B. Busey, 

 A.B., R. Garrett, O. L. Herndon and A. C. Schertz, A.B. 



" The visual acuity of the left eye was less than that of the right. 



