564 BIOLOGICAL EFFECTS OF RADIATION 



particles certainly could not have penetrated through the coats of the 

 particular seeds used. Gager (7) exposed 16 wheat grains to polonium 

 alpha particles and found, 11 days after planting them, that the average 

 shoot length of the resulting seedlings was 123 mm., while the correspond- 

 ing figure for the controls was 76 mm. However, he planted the irradi- 

 ated grains all in one pot and the controls in another. The observed 

 acceleration of germination may have been due to some factor other than 

 the radiation. Stoklasa and Penkava (21, pages 359-360) report a 

 favorable effect of alpha particles upon germination of seeds of Picea 

 excelsa and Pinus silvestris. However, their data as a whole show that 

 the reported increases are not statistically significant. Moreover, they 

 germinated the irradiated and control lots in separate vessels and report 

 no use of duplicates. 



Stoklasa and Penkava (21) report various other cases of acceleration 

 of vital processes by minute quantities of radon and ascribe the effects to 

 alpha particles. For example, the carbon dioxide production of fish 

 (Cyprinus carpio) is increased (21, pages 877-879) by a concentration of 

 2.9 X 10"* mc. of radon per liter in the gas phase of the respiration 

 chamber. Here, as in other cases, the authors find that the alpha 

 particles have an effect opposite to that of beta and gamma rays from a 

 tube preparation of radon. The following figures summarize their 

 results : 



Deviation of Carbon 

 Dioxide Production from 

 Radiation Controls, Per Cent 



Alpha 39 . 39 increase 



Beta and gamma 15 . 75 decrease 



Gamma (experiment 1) 6.11 increase 



Gamma (experiment 2) 19. 23 increase 



These results are very difficult to understand, since it is very doubtful 

 that the beta rays could reach the fish. Practically all of these rays 

 would have been stopped by 1 cm. of water, and the authors mention 

 no precautions to keep the fish near the top. Failures (such as this one 

 and others mentioned above) to take properly into account the physical 

 properties of these various radiations, are conducive to a general lack of 

 confidence in the results reported by these authors. 



EFFECTS UPON SINGLE CELLS, PARTS OF CELLS, AND SMALL GROUPS 



OF CELLS 



Every paper reviewed under this heading describes the production 

 of marked abnormality in the biological material. No favorable effects 

 have been described, although in some cases these should have been 

 observable if actually produced. 



Chambers and Russ (1) found that alpha rays hemolyze red cor- 

 puscles. Two methods were used: (a) solution of radon in a suspension 



