290 



O. HUG AND H. J. SCHLIEP 



Fig. la 



Fig. lb 



nearly linear curve with a much flatter slope (see Fig. 3(a) and the first 

 part of 3(1)). With the arrangement used, a significant contraction could 

 easily l)e registered under irradiation with a dose-rate as low as 330 

 r/min. The increase of the dose-rate shortens the interval between the 

 start of irradiation and the beginning of a visible contraction from about 

 a minute to seconds, the slope of the S-shaped and the quasi-linear 



