The Illumination of Microscope Objects. 
403 
— 
Amount of glare 
1-3 N.A. 
aperture in 
condenser 
Aperture 
of condenser at 
which glare 
disappears 
Aperture j 
of condenser at 
which glare 
lessens 
considerably 
Increase in glare 
caused by op en- 
ing aperture of 
condenser from 
0-65 N.A. to 
1 N.A. 
1. Plain 3 xl slip 
0-043in.thick 
in oil immer- 
sion contact 
with conden- 
ser 
Practically 
none 
1*3 N.A. 
None 
2. Pleurosigma 
angulatum 
mounted 
under cover 
glass in air, 
slip 0-0425 in. 
thick, in oil 
immersion 
contact with 
condenser 
Marked 
0-15 N.A. 
0-16 N.A. 
Marked 
2a. Ditto, not in 
contact with 
condenser 
Very marked, 
diatoms 
appeared 
illuminated 
on dark spot 
0*45 N.A. 
Marked 
3. Diatoms 
mounted in 
realgar in oil 
contact with 
condenser 
Marked, 
rather more 
than 2 
0*25 N.A. 
0-7 N.A. 
Marked 
3a. Ditto, not in 
contact with 
condenser 
Excessive. 
Black spot 
almost 
invisible 
0-2 N.A. 
0-4 N.A. 
i Excessive, 
j Rapidly im- 
proves between 
0*6 N.A. and 
1 N.A. 
4. Diatoms in 
styrax in oil 
contact with 
condenser 
Marked. 
Intermediate 
between 
2 and 3 
0*25 N.A. 
0-6 N.A. 
Marked 
4a. Ditto, not in 
oil contact 
with con- 
denser 
Very bad. 
Not quite 
as bad as 3 a, 
but worse 
than all others 
0-35 N.A. 
Very great 
5. Malaria para- 
site in balsam 
in oil contact 
with con- 
denser 
Very faint, 
as 1 
0*35 N.A. . 
None 
None 
5a. Ditto, not in 
oil contact 
with con- 
denser 
Faint, more 
than 5, less 
than 2 
0*65 N.A. 
j Just notioe- 
able 
