27 
In the first place it appeared, that also after the dark-growth 
response is finished and the growth after + 30 min. 
has grown fairly constant, internally in the metabo- 
lism the dark-equilibrium has not been attained by far 
and will recover itself only after one and a half to 
two hours. 
During the adaptation process the points of time may be defined 
fairly exactly for a fixed light-portion as threshold. For instance 
32 M.C.S. gave after 25, after 26, after 27 min. no reactions, after 
284 min. three responded, one did not. In connection also with 
fig. 2 and 3 on the further increase of the reaction we see that 
the response of growth “turns up” quickly, when once the adaptation 
has sufficiently advanced for that light-portion. When however the 
dark-adaptation has for the greater part been attained, those time 
limits are fainter, since the sensitiveness does not increase eid: 
as during the full adaptation-process. 
The rate at which the sensitiveness increases and rises to the end- or 
dark-sensitiveness, may be imagined by observing in the table that 
from 5— 70 min, thus during by far the greatest part of the 
adaptation-process, respect. in 13, 105, 124, 14 and 15 min. the 
sensitiveness becomes every time 8 times greater. Between 18 and 
284 min. the geometrical rise appears to be strongest, between O 
and 5 min. it is geometrically yet a little slighter than between 5 
and 18 min. By representing in a system of coördinates the times 
as abscissae, as ordinates the logarithms of the values of sensitive- 
DONKER— ADAPTATIE. 
STUGING VAN DE LOGARITHMEN 
DER GEVOELIGHEIDSWAARDEN VOOR 
PHYCOMYCES NITENS ( ) EN VOOR 
DEN GEZICHTS ZIN (IIII,IV, NAAR 
GETALLEN VAN PIPER). 
50 60 70 80 90 100 110 MIN 
Fig. 4. 
Dark-adaptation. Rise of the logarithms of the values of sensitiveness for 
Phycomyces-nitens (..... ) and for the sense of sight (II, Ill, [V according 
to figures of Piper). 
