660 



LATENT PERIOD OF MYA 



as the minimum exposure necessary to produce the minimum reaction 

 time. 



In Fig. 1 are given the detailed results of one experiment with 

 four animals. Each point represents an individual determination of 

 the reaction time at the exposure indicated. The soHd hne joins the 

 averages of the four readings for each exposure period. The figure 

 shows, that though the experimental error is large, the changes in 

 the reaction time for different exposures are well beyond the varia- 



O COS O./O O./S O.ZO 0.25 



Exposure —^ iSeconds 



Fig. 2. The relation between the reaction time and the exposure period at 

 four different intensities. The symbol mc means meter candles. The points are 

 the averages of four determinations, one each on four animals. 



tions due to the experimental error. Data for four other animals 

 are recorded in the points of Fig. 2. Each point is the average of 

 the reaction time of the four animals, one determination having 

 been made on each animal for every exposure. 



The trend of all the experiments is sufficiently clear from those 

 presented in the two figures. They all show that the longer the 

 exposure, the shorter is the reaction time. The difference between 



