6o 



Scientific Proceedings (47). 



The results, stated briefly, are as follows: The average pupil- 

 dilatation in six experiments with 1/50 c.c. of adrenalin per kilo 

 animal was 1.62 mm., with a beginning recovery from dilatation 

 in four minutes, and a complete recovery in ten minutes. 



In six experiments with 1/30 c.c. there was an average dilata- 

 tion of 2.25 mm.; recovery began in eight minutes and was com- 

 plete in twenty-eight minutes. 



In thirteen experiments with 1/20 c.c, there was an average 

 dilatation of 3.61 mm.; recovery began in six minutes and was 

 complete in thirty-seven minutes. 



In eight experiments with 1/10 c.c, there was an average 

 dilatation of 3.87 mm.; recovery began in ten minutes and was 

 complete in forty-nine minutes. 



Finally, in eight experiments the dosage was 2/10 c.c. Here 

 the average dilatation was 4.25 mm.; recovery began in twenty- 

 five minutes, and was practically complete in an average of one 

 hundred and eight minutes. 



In other words, 1/50 c.c. of adrenalin per kilo animal was prac- 

 tically the minimum amount that could be relied upon to give a 

 definite dilatation; as the dosage of adrenalin was increased, the 

 dilatation also became greater, remained at its maximum for a 

 longer time, and the return to a normal diameter was slower. 



42 (651) 



Intermittent and continuous lights of equal intensity as stimuli. 



By G. H. PARKER and B. M. PATTEN. 



[From the Zoological Laboratory of the Museum of Comparative 

 Zoology at Harvard College.] 



It is generally assumed that white lights of equal intensity 

 give equal stimulation. We have attempted to ascertain whether 

 there is any observable physiological difference between the action 

 of continuous white light and intermittent white light of equal 

 intensity. From a common source of light two beams were con- 

 ducted over separate paths of equal length to a common observa- 

 tion point. One beam passed through a narrow slit and was thus 

 reduced to a continuous stream of light of low intensity. The 



