doses on the basis of time it took for lateral 

 roots to appear. If the lateral roots appeared 

 two days later than in the control plants, it 

 meant that 35% of "full dose" was given. A 

 delay of one day indicated 25% of a "full dose. " 

 However, if 10% of a "full dose" was applied, 

 the lateral roots appeared sooner (see Chapter 

 4). These observations indicate that Jungling 

 was seeking a biological dosimeter by his 

 experiments. 



Schwarz, Czepa and Schindler were more 

 categorical in their denial of the stimulating 

 action of X rays. Having set up experiments in 

 1923 with 12 different species of plants (wheat, 

 barley, oats, peas, beans, broad beans, mus- 

 tard, lettuce, Onobrychis , and three field 

 grasses), they did not succeed in establishing 

 stimulating doses. They believed that the 

 major error of the majority of X-ray biologists 

 was caused by using insufficient numbers of 

 samples in their experiments, making it impos- 

 sible to do away with individual differences. 

 However, they were able to confirm the depress- 

 ing effect of high doses of radiation on plant 

 growth. 



In 1923, Sierp and Robbers attempted to 

 introduce a new factor into X-ray research by 

 examining the growth of separate organs and 

 thus were able to analyze the X-ray effect in 

 detail. They used sprouts of A vena sativa , 

 whose coleoptiles are extremely sensitive. 

 These experiments indicated the necessity of 

 considering detailed examinations. For ex- 

 ample, the sheathing of sprouts of Gramineae 

 was extremely sensitive, but difficult to detect 

 if only overall growth is observed. However, 

 it shows up clearly if the various stages of 

 development are observed. After a certain 

 acceleration of growth the authors noted its 

 retardation which became more evident as 

 exposure length was increased. 



Lallemand (1922 [1929?]), limited her obser- 

 vations to the biological effects of X rays on the 

 first stages of development of seeds of Panicum 

 miliaceum , Lepidium sativum , Brassica napus , 

 Triticum sativum , Lens esculenta , Phaseolus 

 vulgaris and onion bulbs. Plant growth was 

 measured on the 14th day after irradiation on 

 the basis of the following considerations: 1) the 

 injurious effects of X rays on plants become 

 more pronounced with passage of time after 

 exposure; and 2) plants cannot be cultivated on 

 water indefinitely without affecting plant develop- 

 ment. Roots, stems, lateral roots, leaves, and 

 hypocotyls were measured. 



Lallemand divided her investigations into two 

 parts: one group of plants was subjected to 

 weak doses of X rays, and others, to medium 

 and strong ones. Seeds of the first group 

 included: Phaseolus vulgaris , Lepidium sativum , 

 Brassica napus, Panicum miliaceum , and Lens 

 esculenta. The seeds designated for the 



experiment were divided into 16 samples: 8 con- 

 trols and 8 others irradiated by X rays in 1/12, 

 1/4, 1/3, 1/2, 5, 10, and 20 H which, with the 

 apparatus she was using, corresponded to 5, 15, 

 and 30 seconds and 1, 3, 5, 10, and 20 minutes. 

 The number of seeds varied with the species of 

 plant being irradiated. After irradiation the 

 plants were placed between two layers of cotton 

 in petri dishes, and at given intervals the 

 sprouting seeds were counted. These experi- 

 ments showed that these doses of X rays failed 

 to have an accelerating influence on either dry 

 or soaked seeds. In order to test the effect of 

 X rays on growth rate, experiments were set 

 up with germinated seeds of lentils, wheat, and 

 dried kidney beans. From these experiments 

 the author concluded that the weakest doses of 

 X rays do not stimulate plant growth. As for 

 the second part of the experiment, i. e. , the 

 action of medium and strong doses of X rays, 

 Lallemand set out to clarify two questions: 1) 

 do very strong doses of X rays destroy the 

 ability of seeds to germinate and 2) do medium 

 doses delay the time of appearance of sprouts. 

 Experiments were set up with various types of 

 beans and lentils. In her experiments the 

 author did not succeed in establishing the inhibi- 

 tion or retardation of sprouting. In exposing 

 1000 germinated lentil seeds to various doses 

 of X rays and then measuring the length of 

 stems, roots, and lateral roots, it turned out 

 that decrease in length is directly proportional 

 to increase of dosage received by the seeds. 



The experiments of Altmann, Rokhlin and 

 Gleikhgevikht were set up with unusual thorough- 

 ness for their time (1923). In the first place, 

 they used seeds of a pure strain of Vicia faba 

 from a single crop and of identical weight 

 (which was determined on torsion scales). In 

 addition, they triplicated their experiments and 

 irradiated seeds in various states (dry, soaked, 

 and germinating). The sprouting and develop- 

 ment of young plants were minutely observed: 

 the appearance of lateral roots and first leaflets 

 was noted; the length of roots, stems, and size 

 of leaves were measured. These observations 

 brought the authors to the following conclusions: 

 1) by gradually increasing dosages it is possible 

 to obtain a transient acceleration of develop- 

 ment, which carries within itself the seeds of 

 a depression of development, which depression 

 is inversely proportional to the brevity of the 

 acceleration; 2) the "stimulating dose" changes 

 depending on the stage of development (for dry 

 beans it was between 6 and 12 H, for germinating 

 ones, between 1 and 3 H). 



Investigating the problem of the accelerating 

 and retarding effect of X rays on the plant de- 

 velopment, Czepa, in 1924, irradiated seeds of 

 Vicia faba , Vicia Sativa , Phaseolus vulgaris , 

 and lettuce with various doses of radiation, 

 ranging from 1/2 to 25 H. Only in one experi- 

 ment did he observe acceleration of growth in 

 the plants used by him. In all the others he 



