474 S. O. MAST 



ps3^chic phenomena involved in the reactions of animals. One 

 of the points of identity that he undertook to establish referred 

 to the relation between color and stimulation in plants and ani- 

 mals. He rejected the results obtained by earlier investigators 

 (Lubbock, Graber and others) which militated against his idea 

 of identity, on the ground that the method employed by these 

 investigators is faulty. They ascertained in which of two or 

 more colors the organisms tend to aggregate, i.e., they used the 

 so-called preference method. Loeb maintained that the results 

 thus obtained have no bearing on the question as to the rela- 

 tion between color and orientation, the phenomenon primarily 

 involved in his idea of identity. He consequently studied 

 directly the effect of color on orientation. 



His methods in the earlier work ('90) were, however, very 

 crude. He used onty two different colors, red and blue, and the 

 constitution of neither was known, being produced by colored 

 glass or colored solutions. Observations were made on the fol- 

 lowing animals: musca larvae, plant lice, caterpillars of Por- 

 thesia chrysorrhoea, moths of Sphinx euphorbia and Geometra 

 piniaria, various copepods, the meal worm, Tenebrio molitor, 

 and larvae of the June bug, Melolontha vulgaris, Limulus poly- 

 phemus and Polygordius. Loeb maintains that all of these ani- 

 mals responded in blue just as in white light and in red just as in 

 darkness, and he concluded that in this respect the reactions in 

 plants and animals are identical, in spite of the fact that Kraus 

 ('76) had demonstrated that the stalks bearing the perithecal 

 heads of the fungus, Claviceps microcephala, turn toward the 

 light nearlj^ as rapidly in the red as in the blue and Brefeld had 

 obtained similar results for Pilobolus microsporus and Pilobolus 

 crystallinus. In 1910 Loeb for the first time made use of spec- 

 tral colors. He and Maxwell tested Daphnia, Balanus larvae 

 and Chlamydomonas using the preference method, so severely 

 criticised in his earlier work, and found the green or yellow region 

 in the spectrum to be the most effective for all, thus confirming 

 the results obtained on Daphnia by Bert ('69) and Lubbock ('81) 

 which had been rejected in his earlier work. 



