“Studies of the effects of radium on plants and animals,” with demonstrations

Abstract

The various studies of the effects of radium that are included in this communication were carried out at the writer's suggestion and under his general direction. All of them are still in progress. They were made possible by the generosity of Mr. Hugo Lieber, who gave the writer an abundant supply of radium bromid for each series of experiments. Professor William Hallock also encouraged the work by permitting the use of some of his valuable samples of radium bromid and radioactive substances. Dr. G. B. Pegram has given advice freely on physical matters connected with radioactivity. The studies included in this plan were the following (I-V): 1

1. “Preliminary notes on the effects of radium rays on plants”: C. STUART GAGER (New York Botanical Garden).

The radium (bromid) has been employed in several forms, and in degrees of activity ranging from 10,000 to 1,500,000. Experiments so far indicate that the effect is the same in kind, whether the plants are stimulated with gamma rays only, or with alpha and beta rays as well. When three kinds of rays are employed the effects, within the same time, seem to be increased. The results already obtained justify the following statements:

The early stages of seed germination are accelerated, if stimulation ranges between the minimum and optimum points, otherwise they are retarded. Seeds are less sensitive to the rays when dry than when soaked. When germinating seeds are exposed to radium at short distance, germination and subsequent growth are retarded, but when the distance between the radium and the seeds is increased and a screen of metal is interposed, growth is accelerated, Radium rays acting through soil in which plants are growing accelerate both germination and subsequent growth of the shoot, and increase the number and length of root hairs.