18 
Erperiments. 4 cells adapted to 64 M.C. and then left in the dark 
show after adaptation to the dark (after 15 — 2 hours) a change in 
growth of —6.0°/, (+ 0.53): 14 cells from another series of expe- 
riments — 7,5°/, (+ 1,2). With one of these 18 cells the growth 
had increased after a 2 hours’ stay in the dark, with two the 
growth was the same, with 15 decreased. 
The cells from the dark, adapted after a few hours to light of 
GROEIREACTIE OP DONKER EN LIGHT 
|= 
BGM Maa B4MK 4: 
0 IO 20 30 40 MIN. 
Fig. 1. Response of growth to dark and light. 
