LAURENS: MONOCHROMATIC LIGHTS. 273 
TABLE 4. 
Comparison of the reactions of normal toads to blue light received through 
both the eye and skin, through the eye only, and through the skin only, with those 
of eyeless toads under the same conditions. 
Condition of toads Normal Eyeless 
Directions of + )/—;}+;O0;+ )|— |x] O 
” Eye and skin 167°, |. (25 147 | 39 6 
Ee pel ses { Eye region only | 170 | 22 13. |14 | 75 | 90 
is Skin only 152 | 40 120, | 43, ee 
vo 
a ' Eye and skin 87 | 13 at | 20 3 
5 . es Eye region only| 89 | 11 fi TBO AT 
| iSkin only i ie Ni | Te | 22 4 1 
The numbers under + indicate total numbers of reactions toward the light; 
under —, away from the light; under +, without reference to the light (indifferent) ; 
under O, no reaction within fifteen minutes. 
results obtained with hooded normal toads (Table 3), though it will 
be noted that in the former case there were 3 % of indifferent reactions. 
These results show that the hoods were an effective method of pro- 
tecting the eyes from the light. But when only the region of the eye 
was exposed to the light, a large percentage of no reactions was ob- 
tained, with almost as large a percentage of indifferent reactions. 
The 7 % of positive and negative reactions were probably accidental 
turnings. There can be no doubt, therefore, that the method em- 
ployed for exposing only the eye was an effective one, and that the 
reactions obtained were due to the effect of the light on the eye, and 
not in any way to the illumination of the small area of skin around it. 
Since this narrow beam of light (blue) showed no power to stimulate 
the region of the eye after the eye itself had been removed, it was 
thought desirable to test the reactions of eyeless toads when this 
beam of light was thrown upon certain regions of the skin. Three 
regions were selected, and these may be roughly described as the 
region of the fore-leg, the region of the hind-leg, and the region of the 
back. 
