Abstract
The in vitro cultivation of embryonic tissues seemed to us the most promising method of gaining important information of the biological reaction of growing tissues to radiant energy. Up to the present, experimentation along physical lines has claimed major interest, and very scant attention has been paid to the biological importance of radiant energy. Consequently very little is known concerning the biological phenomena accompanying radiation.
It was highly desirable therefore to study the immediate and latent behavior of tissues growing in vitro, when placed in immediate contact with radium salts and radium emanations.
The experiments to be reported were conducted upon chick embryo hearts, embryo spleens, and upon Flexner-Jobling rat carcinoma. Along with these, numerous experiments were made upon the effects of radium salts, radium emanations, as well as X-rays, upon different media, such as plasma, serum, embryonic tissue extracts, etc.
In the present studies chick embryo hearts from 7 to 11 day embryos, and spleen from 18 to 20 day embryos were used for in vitro studies. Small fragments were planted in a medium of chicken plasma and embryonic tissue juice. In the cultures where spleen tissue was used, the embryonic tissue extract was omitted. Fine glass seeds about 0.5 centimeter in length, and 1 millimeter in thickness, containing 0.1, 0.25, 0.35, 0.5 millicuries to 1.0 millicurie of radium emanations, were placed in direct contact with the tissue, or, 1 and 2 millimeters distant.
A series of 12 experiments were conducted comprising 100 cultures, without radium or with empty glass seeds. Growth was charted by using the camera fucida, and the area of new growth measured with the planimeter one hour, 24 hours, and 48 hours after incubation. After this period subculturing was continued.
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