REACTIONS OF NERVES AND MUSCLES TO RADIATION 



291 



Fig. 1(c) 



Fig. 1. — Nerve -muscle preparations. Cessation of spontaneous rhythmical activity after 



X-irradiation. 



(a) — Earthworm: 115 r/min. Irradiation time 10 sec (without effect) and 15 sec. Time 

 marks: 5 sec. 



(b) — Earthworm: dose-rate 4,000 r/min. Irradiation time 1 and 2 min. Time marks: 

 5 sec. 



(c) — Leech: dose-rate 13,200 r/min. Irradiation time 2 min. Time marks: 1 min. 



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Fig. 2. — Nerve-muscle preparations of the earthworm. Induction of rhythmictil motion 

 and increase of average tonus by irradiation with a dose-rate of 100 r/min. Irradiation 



tiine 15 sec. Time marks : 5 sec. 



part of the curve becomes steeper and the plateau which the sigmoid 

 part of the curve tends to approach becomes higher. Under irradiation 

 with very high dose -rates the sigmoid part of the curve reaches a 

 real plateau. The latter corresponds to the largest possible con- 

 traction of the muscle amounting to about 55 per cent of the initial 



