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This work was done to explore the causes of sleep movements in Oxalis. Several methods were employed to discover the answers to speific questions concerning Oxalis nyctinasty.

The question of the control of Oxalis leaf movement by a typical biological clock and problems of the parameters of photic control are answered with the help of light control chambers and time-lapse photography. An anatomical study of the pulvinus, or motile organ, is described. Physiological studies consisted of tests for the site of activity of light and color of light active, as well as comparisons of the action on pulvini of externally applied IAA with the action of pulvinar extract.

Oxalis nyctinasty is not under direct control of a biological clock. Closing takes place in darkness and opening takes place before, dawn the next day. The ability to close for a long period of time in the dark period following a light exposure is conferred by light in the morning hours, and the length of afternoon light and time of sunset determine the actual time of opening. Length of time closed is a seasonally determined quantity. The properties of a hypothetical controlling substance are outlined.

The peculiar action of blue light on the parenchyma cells of pulvini suggests that an auxin is the active material in Oxalis nyctinasty. A possible mode of action of IAA is suggested. Externam application of indoleacetic acid to pulvini make them act in a manner suggestive that those applications are additive to a similar material already present. Applications of pulvinar extract to pulvini produce an effect similar to IAA. Ohromatographic separation and identification of auxin compounds suggest the presence of indole, an IAA derivative, but are inconclusive.

Evidence suggest that IAA is the active material in Oxalis nyctinasty.



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Degree Name


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Department Name

UNM Biology Department

First Committee Member (Chair)

Leonard Patter

Second Committee Member

William Jacob Koster

Third Committee Member

William Clarence Martin

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