328 



bulletin: museum of comparative zoology. 



TABLES IV AND V. 



Time of exposure varied. Distance constant at 150 cm. Evaluations made 

 with reference — 



Table IV — to a single standard condition of medium migration, — - 

 Table V ^ to three graded migrations exhibited by animal 22. 



A computation from the average evaluations for R at 30 minutes and 45 

 minutes and with reference to that of BV at 5 minutes jnelds by interpolation : 

 From Table IV, BV at 5 minutes = R at 36.8 minutes 

 " " V, BV at 5 minutes = R at 39.0 minutes 



Av. = 37.9 minutes 

 or BV = 7.6 R in terms of time of exposure required. 



In Tables IV and V are given also a few evaluations for exposures 

 to red at 50 cm. for five minutes. When the average of these is 

 compared with the average of the exposures at 150 cm. for forty-five 



