1004 BIOLOGICAL EFFECTS OF RADIATION 



Ingber (39), studying Vicia Faba var. minor, reported stimulation 

 of function and also lesions. The second of two papers contains a review 

 of the present (1931) state of radiobiology and a bibliography of 16 pages. 

 In the same year, Kessler and Schanderl (40) reported on studies of the 

 effect of rays of different intensities. 



Montet (55, 55a, 56) reported on the effect of weak radioactivity 

 on germination, and of radium rays on the germination of bulbs. With 

 the bulbs the foliage was stronger and greener, the flowers were larger, 

 and their color was more vivid. 



Zirkle (88) studied the effect of the rays from Polonium (radium-F) 

 on cells. The rays given off by the material used were only alpha rays. 

 It was found that these rays retard and inhibit three distinct processes 

 in the germination of the spores of Pteris longijolia, viz. : cracking of the 

 sporewall; development of chlorophyll; and cell division. Extranuclear 

 irradiation produced a high frequency of a type of induced twining. This 

 paper has a bibliography of related papers. 



Doubtless the most exhaustive publication on the effect of radium 

 rays on plant life since 1908 is the treatise by Stoklasa and Penkava (81). 

 This contains bibliographies covering the entire subject from the first 

 experiments, and is an indispensable handbook for those engaged in 

 investigating this subject. 



For the readers' convenience, papers dealing with the effect of radium 

 rays on heredity are grouped together in the following paragraphs. 



At the 1926 meeting of the Botanical Society of America, Gager and 

 Blakeslee reported on experiments in subjecting germ cells of Datura to 

 radium rays, and their paper appeared in February of the following year 

 (26a) giving data concerning the appearance of both chromosome and 

 gene mutations in that genus. The material exposed consisted of 

 pedigreed plants in the cultures of Dr. Blakeslee at Cold Spring Harbor, 

 Long Island. In the formation of one of the new forms ("Nubbin") 

 that resulted from the radium treatment, there occurred a breaking 

 up and reattachment of parts of nonhomologous chromosomes. The 

 treatment was effected by inserting capillary tubes of radium emanation 

 into the cells (compartments) of the ovary, or into the walls between 

 the ovary cells. In one experiment the radiation had a strength of 

 13 millicuries, and the time of exposure was 10 min. At the time of 

 treatment reduction had certainly already taken place in the pollen 

 mother cells and almost certainly also in the megaspore mother cells. 

 Seeds from the four ovary cells were kept separate in the sowing. The 

 number of mutants varied from 11.54 per cent in seeds from one cell 

 to 28.57 per cent in seeds from the cell into which the emanation tube 

 was inserted. The chromosomal types resulting were mostly 2n + 1 

 forms. Cell 1 gave rise to one 2n + 2 type, called "Globe," and also 

 to "Nubbin" mentioned above. 



