Abstract
* Accepted for publication by C. J. Warden of the Editorial Board and received in the Editorial Office, March 29, 1934. 1 Acknowledgment is gratefully made to Dr. C. G. Hartman of the Department of Embryology, Carnegie Institution of Washington, Baltimore, Maryland, for the donation of the subject of known gestation age, and to Dr. C. J. Warden, of the Laboratory of Comparative Psychology, where the investigation was carried out.

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