562 BIOLOGICAL EFFECTS OF RADIATION 



deposited upon free metallic surfaces. The radiation from such a source 

 is homogeneous. Doses can be calculated with certainty and precision. 



EFFECTS UPON MACROSCOPIC STRUCTURES AND SYSTEMS 



Not many papers can be definitely placed in this category. The 

 low penetration of the alpha particles usually insures that the observa- 

 tions of effects will be made upon individual cells and not upon gross 

 morphological structures. Moreover, a number of investigations with 

 radon cannot be included because it is uncertain whether the reported 

 results are ascribable to alpha particles or to beta and gamma rays 

 emitted by the decay products of radon. 



Zwaardemaker (29) reports that alpha particles, as well as beta 

 radiation, will compensate for the omission of potassium from the Ringer 

 solution ordinarily used in maintaining the normal beat of an isolated 

 frog's heart. He accordingly ascribes the essential role of potassium 

 in this solution to its radioactivity. Polak (15) confirms these results. 

 Zwaardemaker also reports that the effect of alpha particles is antagonized 

 by an appropriate simultaneous dose of beta rays. This he ascribes to 

 the charge of the beta rays (electrons) being opposite in sign to that of 

 the alpha rays. As Redfield and Bright (18) point out, this seems very 

 improbable in view of the fact that the ionization due to both types of 

 radiation produces electrical disturbances which are tremendous com- 

 pared to those which could be produced by transfer of the charges carried 

 by the alpha and beta particles. 



This view that the biological effects of alpha particles are due to 

 their positive charges has also been expressed by Straub and GoUwitzer- 

 Meier (22) who report experiments which indicate that alpha particles 

 facilitate the loss of negative charge and the assumption of a positive one 

 by human red blood cells. Hardy (8) also invoked the charges of the 

 alpha particles to explain his observation that this radiation coagulated 

 serum globulin in alkaline solution (globulin charged negatively), while 

 an acid solution (globulin charged positively) became clearer. However, 

 in both these cases, the observed results could be qualitatively explained 

 by the assumption that the fundamental effect of the alpha particles 

 was the removal of electrons from (or ionization of) the red-cell con- 

 stituents and the globulin molecules, respectively. Moreover, with this 

 assumption, one could account for some 10,000 to 15,000 times as much 

 removal or addition of charge as could be brought about by means of the 

 charges carried by the particles themselves. 



Chambers and Russ^ observed what may be an instance of qualitative 

 difference in biological effects of alpha rays and of beta rays. When 

 both alpha and beta rays were used on a suspension of bacteria, marked 

 agglutination occurred before the lethal point was reached. If the alpha 



^ Original paper not available. See Colwell and Russ (2), p. 162. 



