EVALUATION OF PLATEAU'S RESEARCHES. 211 



they alighted to forage only on the mutilated blossoms deprived of corollas.' [The italics 

 are Plateau's!] And Plateau concludes that it is smell and not vision that guided 

 them! Is it possible to prove better to oneself the contrary of what his experiment 

 says? That bees do not forage where there is nothing, is obvious to a child. But 

 that they should seek the flowers, wherever they perceived them, by their bright 

 yellow color, that they should see the dry rudiments or the buds on the plant, this 

 agrees so admirably with our experiments that I pass no comment. 



"The last conclusions of Plateau are somewhat curious. He begins by declaring 

 that he has 'never said that insects do not see the colors of flowers; that would be 

 absurd' (jievertheless, he uses the title: On the so-called distinction of colors by insects). 

 Then he adds that the differences in the quantities of reflected light or in the refran- 

 gibility of luminous rays transmitted or reflected by the transparent media can explain 

 the results hitherto obtained. And finally he pretends that the question to be solved 

 U: do the insects which visit flowers allow themselves to be guided in their choice 

 by the colors which these flowers present to the human eye? I protest against the man- 

 ner in which Plateau now puts the question. I do not believe any more than he does 

 that insects see colors subjectively as we do, and I believe further with him that there 

 are objective differences in the manner in which their eyes and ours are stimulated 

 by the different forms of light, i. e., by colors and shades. But the experiments of 

 Lubbock, of Peckham, of other authors, and my own indicate that certain insects 

 distinguish not only flowers, but colored objects, by their coloration, i. e., by the kind 

 of refrangibility of the luminous rays which they reflect or transmit, and recognize 

 them in this particular when the other senses are eliminated, and even when such 

 objects are found surrounded by light of the same intensity. 



"In saying that bees distinguish colors, We have never wished to assume that they 

 see them exactly as man does, and so much the less since, as I have already emphasized, 

 all men do not see them absolutely the same. 



"In recapitulation, we see that the facts are very complex, and this is why I abstain 

 from general conclusions on 'all insects' seeing or not seeing 'forms and colors, etc.,' 

 for such generalization would necessarily be false. If one wishes to understand it, 

 one must take the trouble to follow the details. Nevertheless, I am constrained to 

 repeat that Plateau's interpretation of his so-called non-distinction of forms among 

 insects, after the restrictions which he has himself gradually introduced, finally 

 approaches more or less to the opinion of Exner, which has always agreed with my 

 own. The greatest error of fact into which Plateau falls, is that by which he attributes 

 what really belongs to vision in certain insects (in bees in particular) to their 

 sense of smell. Nevertheless, in the final paper of the series, he finally recapitulates 

 the way insects guide themselves, in a manner which in its general characteristics 

 approaches nearly to the truth. As we have seen, the causes of the erroneous judg- 

 ments with which Plateau has obscured the question at issue are errors of interpreta- 

 tion, inadmissible and continual generalizations, and the almost total neglect of the 

 psychical faculties of the insect, especially with regard to memory and association." 



Although Forel's criticisms of Plateau's work are often too severe, 

 they are on the whole fairly well justified. They err in making the dif- 

 ferences between their general conclusions greater than it actually was, 

 as Plateau himself pointed out (1902 2 :424). Moreover, Forel was not 

 free from the contradictions for which he takes Plateau to task, and it 

 is evident that his own knowledge of the behavior of anthophilous in- 

 sects was much smaller than for many other groups. After dismissing 

 the views of Mueller and Lubbock on color preference as unsatisfactory 

 or inconclusive, he states that "this problem is so difficult and delicate 

 to decide that I dare not express an opinion," only to express a very positive 



