FOULING OF SHIPS' BOTTOMS 



245 



yellow, the stimulating efficiency is equal to more than 50 per cent that of white 

 light; while between 530 and 545 mu-mu it is more than 90 per cent, or virtually 



PERCENTAGE 100- 



O o 5: g o o o o :g si 5= o o 



11 1 1 ! 1 1 I I II" 1 



000 u ji 01 in t/t cr. (ji — ro oj _ 



<jj to en to o to cr> ro co tnrooo <x> 



Fig. 38.— Distribution of the stimulating efficiency of equal energy values among the various parts of the spectrum for the 



cyprid larvae of certain barnacles 



equivalent to white light. On the other hand, light of wave lengths of 700 mu-mu 

 has less than 5 per cent of the efficiency of white light, and likewise at 420 mu-mu 



A. B. C. 



I I i 



Fio. 39.— Attachment of barnacle larva? with reference to source of illumination (indicated by arrows) 



the stimulating efficiency is very much reduced. For a more complete account of 

 these experiments see Visscher and Luce (1928). 



