Figure iMi 



lUo Plan of the tank in which the tuna, used in experiments 



with artificial lightj were kepto oo o _. o c ooo oo « oo oo o ooo oo 38 



l5o Plan of instrument box housing light-producing and 



optical ef^Uipmento OOO.-OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO ,57 



l6o Transmission characteristics of Kodak Wratten filters^ooo hX 



17 o Diagram of the tank (A) and pond (B) showing the 

 position of the transmitter and receiver used in 

 experiments with soundo oo oooooonooooooooooooooooooooooooo ol 



l8o Circuit and apparatus used in 1he electrical experimentSoo 71 



19 o The "revolving disk" mechanical interruptero oooooooooooooo 76 



20o The "plunging electrode" mechanical inter rupter. oo «» 



21 o Trend of average current (and current density) with 

 change in "on-fraction" of a cycleoooo 



I O O O o o o 



too OOOOOO O o ooooooooo 



80 

 82 



