30 
0. The Illumination of the Object. 
The modern microscope is essentially constructed for illumination with trans- 
mitted light. Ordinary microscopic observation demands exclusively illumination 
by white (day or lamp) light without limitation of the tield, but the incident 
pencil should be capable of wide variation as regards its angular aperture (wide 
or narrow illuminating cone) and its direction (central or oblique light). These 
requirements are fulfilled by the ABBE Condenser, first introduced by us in 1878 
(Max Schultze's Archiv f. mikr. Anatomic, IX, p. 413, 1873), and now so gener- 
ally employed and so universally acknowledged as an indispensable accessory in 
advanced microscopic work, that it forms an essential adjunct to 
intended for scientific research. For description vid. Nos 17 to 20 of this 
Catalogue. 
To facilitate the employment of the cylinder diaphragms, which in our 
older stand necessitated the removal of the whole illuminating apparatus previous 
to their insertion, we have a few^ years ago made certain alterations in the 
mechanical arrangement of the Abbe illuminating apparatus, which, at the same 
time, render the frame of the apparatus available for the adaptation of otlier 
illuminators, such as the special ones described in Nos 20—23. 
