THE RELATIVE PHYSIOLOGICAL EFFECTS OF /S-RAYS OF 

 DIFFERENT VELOCITIES. 



By ALFRED C. REDFIELD and ELIZABETH M. BRIGHT. 



(From the Laboratory of Physiology, Harvard Medical School, Boston, and the Marine 

 Biological Laboratory, Woods Hole.) 



(Received for publication, June 17, 1919.) 



Insight into the nature of the action of any reagent upon protoplasm 

 can be gained only through the correlation of its physical and chemi- 

 cal properties with its physiological effects. The present investi- 

 gation is an attempt to discover whether any quantitative relation 

 exists between the physiological effects of /3-rays from radium of 

 different velocities and their physical characteristics. 



At the present time it is impossible to state definitely whether 

 quahtative differences exist in the reactions of tissues to a-, ^-, -y-, 

 and x-rays^ although the characteristic effects in accelerating and 

 retarding cell division and growth appear to be the same. 2- ^ It is 

 also indicated that the magnitude of the physiological action of these 

 various kinds of rays corresponds roughly with their strength, as 

 measured by their action in ionizing air.* 



Several investigators have already undertaken to compare the 

 effects of slow and fast |8-rays from radium, but none of them have 

 attempted to procure homogeneous groups of rays or to determine 

 more than relatively the velocities of the rays used. Packard, who 

 by means of a strong magnetic field and with the aid of mica filters 



^ For evidence of specific effects of different types of rays see Beckton, H., 

 Arch. Middlesex Hospital, 1914-15, xxxii, 123. Chambers, H., and Russ, S., 

 ibid., 1912, xxvii, 29. Colwell, H. A., and Russ, S., Radium, x-rays and the 

 living cell, London, 1915, 146. 



2 Lazarus-Barlow, W. S., and Beckton, H., Arch. Middlesex Hospital, 1913, xxx, 

 47. Packard, C, /. Exp. Zool., 1916, xxi, 199. Richards, A., Biol. Bull., 1914, 

 xxvii, 67. 



* Packard, C, /. Exp. Zool, 1915, xix, 323. 



* Russ, S., Arch. Middlesex Hospital, 1912, xxvii, 16. Lazarus-Barlow, W. S., 

 and Beckton, H., ibid., 1913, xxx, 47. 



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