370 



TIME AND INTENSITY IN STIMULATION 



Only dark-adapted animals are used; and between tests they are 

 kept in complete darkness. At least 15 minutes are allowed between 

 tests. 



At different times during the summer I performed seven series of 

 experiments: one with three animals; two with four animals; two with 

 six animals; and two with seven animals. As an example, Fig. 1 

 gives the data of the series of experiments performed on July 28. 



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Fig. 1. Relation between the reaction time and the intensity of the stimulating 

 light. Experiment 9.28; 40 watt lamp; six animals; three readings for each 

 animal for every intensity. 



The reaction time of each animal was measured at three different 

 times for every intensity. Each point in Fig. 1 is thus an average of 

 eighteen measurements, three with each of six animals. It is 

 apparent that the experimental results are regular and may therefore 

 be treated mathematically. 



