Before the eyelids have opened young rats are negatively heliotropic. They behave very much as does the larva of the blow-fly. The angle of orientation by lights opposed at 180° may be calculated by an equation based upon the elementary requirement of phototropism, namely that orientation is attained when the illumination of bilaterally disposed photoreceptors is equal. The precision of orientation decreases very nearly in proportion to the sum of the logarithms of the acting light intensities, due to photokinetic head movements. When the eyelids are opened, the rats move toward a darkened place in the field of vision, usually toward the shaded region immediately to one side of the lamp house. Therefore, when heliotropic, the rat is not "seeking the dark". The phototropism of these animals may be brought into conflict with their pronounced stereotropism, and the resolution of such conflicts may perhaps be utilized for the investigation of central nervous states.
Article|
January 20 1927
PHOTOTROPISM IN YOUNG RATS
W. J. Crozier,
W. J. Crozier
From the Laboratory of General Physiology, Harvard University, Cambridge.
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G. Pincus
G. Pincus
From the Laboratory of General Physiology, Harvard University, Cambridge.
Search for other works by this author on:
W. J. Crozier
From the Laboratory of General Physiology, Harvard University, Cambridge.
G. Pincus
From the Laboratory of General Physiology, Harvard University, Cambridge.
Accepted:
November 19 1926
Online Issn: 1540-7748
Print Issn: 0022-1295
Copyright, 1927, by The Rockefeller Institute for Medical Research
1927
J Gen Physiol (1927) 10 (3): 407–417.
Article history
Accepted:
November 19 1926
Citation
W. J. Crozier, G. Pincus; PHOTOTROPISM IN YOUNG RATS . J Gen Physiol 20 January 1927; 10 (3): 407–417. doi: https://doi.org/10.1085/jgp.10.3.407
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