THE RELATIVE PHYSIOLOGICAL EFFECTS OF beta- AND gamma-RAYS UPON THE EGG OF NEREIS.

When Nereis eggs are exposed to radiations from a tube of radium emanation, the walls of which absorb all the alpha-rays, the resulting physiological change is produced by rays having a coefficient of absorption of the order of 23.9 cm.(-1) This fact indicates that the physiological effect is due almost exclusively to beta-rays. The gamma-rays alone can produce the reaction. To produce equivalent physiological effects exposure to gamma-rays alone must be approximately 60 times as long as exposure to beta- and gamma-rays together.