ALPHA PARTICLES 563 



rays were screened off, no agglutination took place, although the death 

 point was ultimately reached. Colwell and Russ (2) suggest that the 

 charges on the particles may be responsible for the difference in action 

 in the two cases. A more probable factor is the difference in the distribu- 

 tion of the ions produced by the two types of radiation. 



The relatively tremendous destructive power of alpha particles is 

 demonstrated in an early paper by Willcock (25). This author exposed 

 Hydra viridis to 50 mg. of radium bromide in such a way that the alpha, 

 beta, and gamma rays could all reach the organism. The animal's 

 vitality was low at the end of 1 hr. and disintegration occurred after 

 2 hr. However, when only the beta and gamma rays from the same 

 preparation were allowed to reach the organism, the latter survived for 

 several days after an exposure of 4.5 hr. 



This great destructive ability has recently proved to be of economic 

 and clinical importance. A number of girls, while working with radio- 

 active luminous paint, ingested amounts of radium ranging from 10 to 

 180 micrograms. After several years, serious pathological conditions — 

 chiefly anemias and sarcomas of the bones — developed, and death 

 usually resulted. These effects are almost certainly due to the alpha 

 particles emitted by the radium and its decay products. Martland 

 (13) has summarized these cases, particularly the clinical aspects, and 

 Schlundt, with various collaborators, has described the pertinent physical 

 investigations {e.g., Schlundt and Failla, 20). Thomas and Bruner (24) 

 have recently produced anemias and other pathological conditions in 

 rats by injection of a few micrograms of radium. This work, along with 

 the clinical observations just mentioned, emphasizes the need for investi- 

 gation of the fundamental effects of alpha particles on living matter. 

 As Martland (13) points out, it is possible that the initiation of some 

 malignant growths may be due to the action of radioactive substances 

 normally present in the body in amounts minute in comparison with 

 those concerned in the cases of radium poisoning. 



Stoklasa and Penkava (21, page 739) describe lethal effects of radon 

 upon guinea pigs, mice, frogs, and lizards. These effects are ascribed to 

 alpha particles. The doses reported, however, are surprisingly small. 

 If one calculates the maximum number of alpha particles which could 

 have been emitted per unit time per unit volume of animal (guinea pig or 

 mouse), the figure obtained is less than one-twentieth of that resulting 

 from a similar calculation of the minimum intensity used by Thomas and 

 Bruner (24) on rats. Moreover, the time required for the rats to die 

 under continuous exposure was about 10 times that reported by Stoklasa 

 and his coworker for mice and guinea pigs, so that the ratio of the doses 

 used by the two sets of workers is at least 200:1. 



Favorable effects of alpha particles upon seed germination have been 

 reported at least twice. Such an effect is very surprising, for the alpha 



