l^HE RELATHE EFFICIENCY OF VARIOUS PARTS OF 

 THE SPECTRUM FOR THE HELIOTROPIC REAC- 

 TIONS OF ANIMALS AND PLANTS 



SECOND COMMUNICATION 



JA(X^IK,S J.OEB AND HARDOLPH WASTENEY8 



77/r lioclccfellcr In^lilide for Medical Resenrcli, .Yew; York 



SIX FIGUBES 



In 1869 Paul Bert made experiments on the effect of different 

 parts of the spectrum on Daphnia to find out whether the vision 

 of these crustaceans is comparable to that of man. He found 

 that the animals "accouraient beaucoup plus rapidement au 

 jaune ou au \'ert ciu' a toute autre couleur," and concluded from 

 this that the ^veen and yellow rays which appear comparati\-ely 

 bright to us appear also brightest to these animals.- 



At that time biologists were generally under the influence of 

 the anthropomorphic viewpoint and did not hesitate to interpret 

 the reactions of animals on the basis of human analogies; al- 

 though it must have occurred to as clear a thinker as Bert that 

 there is no a priori i-eason for assuming that human beings when 

 put into a spectrum must gather in the green or yellow; and ex- 

 periments in this direction were lacking. This anthropomorphic 

 \'iewpoint appeared still more plainly in the writings of Graber,- 

 \\h() experimented with animals which were kept in a box illu- 

 minated from al)o^•e, one-half of which was covered with red, the 

 other with blue glass. He found that animals which prefer 



' First Coiuinuuictition. Join-. Exp. Zool., I'Jlo, 19, '2S. See also i.oel) and 

 Wasteneys, Proc. Nat. Acad. 8c.. 1915, 1, 44; Science, 191,5, 41, 328. 



■-Paul Bert. Arch, de Physiol., 1809, 2, 547. 



^ Graber. Gnuidlinien zur FirForschuno; des Hellifikcits- iind Farhensinncs der 

 Tiere. Praji. 1SS4. 



217 



