Samenvatting
The intensity discrimination B/B of the yee at a fixed state of adaption; size of the test field 34; 40; light intensity of the test field 0,1-1000 Apostilb; time of exposure 5 sec. has each time an optimum at the respective light stilb. At lower rates of light intensity, up to 10% of the light intensity of adaption can be distinguished from black; at higher rates, B/ B is but slowly decreasing below 2.