Volume 1

Studies in general physiology / by Jacques Loeb.

  • Jacques Loeb
Date:
1905
Catalogue details

Licence: Public Domain Mark

Credit: Studies in general physiology / by Jacques Loeb. Source: Wellcome Collection.

    32/446 page 12
    The most extended experiments on the influence of light on the orientation of animals were made by Gräber.1 His «/ “comparative studies on light-sensations” (Vergleichende Licht-Gefühl-Studieri), as he called his investigations, cover about fifty species. His method is that followed by Lub¬ bock. The faultiness of this method and the errors of interpre¬ tation of the results obtained stand out more clearly in Graber’s writings than in Lubbock’s. Gräber covers one- half of a vessel with a partially or completely opaque screen, and after a time notes how the animals are dis¬ tributed in the vessel. If most of the animals are under the opaque screen, Gräber says that they are “fond of the dark” and “hate the light;” or in the reverse case, that they are “fond of the light” or of “the white” and “hate the dark.” He therefore uses the conceptions of “white” or “bright” and “dark,” which designate certain effects of light upon a human being for the conceptions of great or small intensity of the light; and in saying that animals which “prefer the light” also “hate the darkness” he makes a second mistake in that he maintains that strong and weak light have opposite effects. We shall see, however, that these effects are similar and differ only in degree. He makes the same mistake in experimenting on rays of different refrangibility. The most important among the facts ob¬ served by him in this connection is this, that animals which “prefer the light” with a few exceptions also “prefer” blue, while those which “hate the light” “prefer” red. His ideas are expressed in the following remarks, which, however, I do not fully understand: The question arises as to the cause of this truly striking rela¬ tion between the love for white light and for blue light, on the one hand, and between the dislike for white light and for blue light, i Grundlinien zur Erforschung des Helligkeits- und Farbensinnes der Thiere (Prag, 1884).
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