170 
light remained constant in the successive determinations of the limits. 
With the experimental person Wa. e.g. the limit value, that is to 
say at little, respectively average, or great brightness of the flickering 
light it was 28.6 respectively 23 or 20 periods per second. 
After the penetration of the strong light-stimulus during 45" re- 
spectively 90" or 180" the successive determinations which were each 
separated from each other by rest-pauses of 10 seconds and lasted 
even about 15 seconds, offered quite a different appearance. 
I summarise the progress of the effect of the fatigue in Table 1: 
This table teaches : 
1. The longer the fatigue lasts, the more the power of distinction 
decreases in the first moment after the cessation of the stimulus 
of fatigue. 
2. The norm, which the achievement indicates at a good adapt- 
ation of light, is however reached in about the same time. So the 
longer the fatigue lasts, the more relatively the process of relaxation 
takes place. 
3. After the norm has been reached again, the power of presta- 
tion rises still higher above the norm and remains for some time 
so much the greater as the primary fatigue was longer. 
This excess of compensation deserves our special attention. 
4. The greater the intensity of the flickering light is, the less 
the prestation descends under the corresponding norm with the 
same duration of the stimulus of fatigue. 
Point 1 indicates how the processes of fatigue constantly prevail 
more and more over the compensatory factors intervening simultane- 
ously, when the duration of the irritation is increased. 
In point 2 the regulations of the efforts of the fatigue are form- 
ulated by the compensatory processes after the cessation of the 
stimulus of fatigue. 
Point 3 indicates the relative duration of these compensatory pro- 
cesses after the relaxation has taken place. 
Point 4 indicates that the consequences of the fatigue do not only 
depend upon the duration of the fatigue, but also upon the original 
stationary condition of the eye that is caused by the intensity of 
the flickering light. 
The comparison of the limit values after the fatigue and after 
the adaptation of light shows consequently a principal difference 
between the two states. The adaptation of light is a stationary state 
of the eye which determines a constant height of the prestation. 
When this state has once been reached, then it is indifferent with 
regard to the time-factor. The fatigue on the contrary creates a 
