When Nereis eggs are exposed to radiations from a tube of radium emanation, the walls of which absorb all the α-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 ß-rays.

The γ-rays alone can produce the reaction. To produce equivalent physiological effects exposure to γ-rays alone must be approximately 60 times as long as exposure to ß- and γ-rays together.

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