180 C. F. CURTIS RILEY 



of paper having a dead black finish. This paper was so arranged 

 that it could be readily removed at either end, thus permitting 

 the rays of light to enter. 



Unfortunately, the writer was unable either to complete the 

 work on the responses to photic and contact stimuli, or to com- 

 mence any experiments on other forms of reaction work. Through 

 an oversight, the water was allowed to dry up in the jar containing 

 the toads, and the next time they were needed for experimenta- 

 tion purposes they were found to be dead. As it was not pos- 

 sible, at the time, to obtain any more material, and as the 

 opportunity to complete the work has not presented itself since 

 then, it was thought best to publish in a brief form the results 

 of the experiments incomplete as they are. The writer hopes, 

 at some future time, to continue the work outlined in this paper 

 in far more detail and to supplement it with experiments on 

 responses to other forms of stimuli. 



Thanks are due to Miss F. J. Dunbar of the Zoological De- 

 partment of the University of Michigan, who kindly collected 

 the amphibians used in these experiments. Mr. S. A. Rowland, 

 of the Physics Department of the University of Illinois, calcu- 

 lated the intensity of the illumination within the field of ex- 

 perimentation employed in this work. His assistance is grate- 

 fully acknowledged. The writer also desires to express his 

 appreciation of the criticisms and encouragement given by 

 Doctor C. C. Adams of the University of Illinois. 



II. RESPONSE TO INTENSE ARTIFICIAL LIGHT 



The first experiments undertaken were with reference to 

 intense artificial light as a source of stimuli. The light em- 

 ployed for this reaction work was obtained from the electric 

 arc of a Thomson " 90 carbon " projection lantern. The current 

 passed from the electric lighting circuit through a rheostat, and 

 from there to the lantern. The current was direct with an 

 approximate voltage of 210. Within the field of experimenta- 

 tion the illumination was approximately 10,000 ca. m. In 

 order to eliminate the effect of the heat rays, the light was 

 allowed to filter through a cell containing distilled water. Hav- 

 ing placed the toads in the glass dish, it was then moved into 

 the beam of light that emerged from the lantern. In order to 

 prevent the organisms from becoming unnaturally dry during" 



