Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published March 1959 | Published
Journal Article Open

Photoreactions in Phycomyes: growth and tropic responses to the stimulation of narrow test areas


Sporangiophores of Phycomyces in stage IV b have been stimulated by parallel light in test areas 0.2 mm. wide. The growth responses to large stimuli are very large, owing probably to light scattered within the specimen. For medium stimuli the sensitive zone coincides with the growth response zone obtained previously and excludes the region of maximum stretch. Sustained stimulations were used to elicit tropic responses. The bends formed travel away from the sporangium at a speed equal to the growth speed. Thus they remain very close to the stimulus when this is held at a constant level relative to ground but separate from it for stimuli programmed differently. The existence of a protoplasmic structure, the "inner wall," with the following properties is postulated: it is attached to the lower, non-growing part of the sporangiophore and grows by addition above the sensitive zone. It neither stretches nor twists in the sensitive zone. It is the seat of the light receptors and gives growth and tropic responses. The cell wall follows its bends by elastic stretch.

Additional Information

© 1959 by The Rockefeller University Press (Received for publication, August 29, 1958) Supported by a grant from the National Science Foundation.

Attached Files

Published - COHjgp59.pdf


Files (1.1 MB)
Name Size Download all
1.1 MB Preview Download

Additional details

August 21, 2023
October 16, 2023