EFFECTIVENESS OF X-RAY WAVE-LENGTHS 



465 



The data show that when equal doses, measured in roentgens are 

 deUvered, the proportion of eggs that survive is very constant. Similar 

 series of tests in which the doses range from 50 to 300 r furnish data for 



90 



80 



20 



10 







50 



100 



200 



250 



300 



It 



as indicated 



150 

 Dose in Roentgens 



Fig. 1. — Curve showing the relation between X-ray dosage and biological effect 

 is based on data derived from experiments in which different wave-lengths, as indi( 

 by the symbols, were used. 



the survival curve shown in Fig. 1. This curve is an expression of the 

 normal variability of the eggs to X-radiation ; it is also a means of meas- 

 uring dosage (28), for the proportion of survivals is an accurate indication 

 of the number of roentgens which the entire sample received. When 

 doses estimated in this way are compared with measurements made with 



