ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
249 
C3) Illuminating- and other Apparatus. 
Fromme’s Arrangement of the Polarization Apparatus for Histo- 
logical Purposes.* — Prof. V. v. Ebner remarks that the arrangement of 
the polarization apparatus in the ordinary Microscope is not very con- 
venient for histological work. Means for measuring the angle of rotation 
of the polarizer, necessary in the case of circularly polarizing substances, 
is not required for histological work. An indispensable requisite, how- 
ever, for such work is an arrangement which allows the preparation to 
be turned through all azimuths between the fixed nicols. The rotating 
Fig. 26. 
stage-plate with which many polarizing Microscopes are provided is not 
suited for work with high powers, owing to want of proper centering. A 
Microscope, however, of which the upper portion together with the stage 
can be rotated about the vertical axis, allows of the rotation of the pre- 
paration between fixed nicols if the polarizer is attached to the lower 
fixed portion of the stand, and the analyser to a special holder which 
does not share in the movement of the Microscope. 
An instrument, answering to these requirements, which waa made for 
* Zeitschr. f. wiss. Mikr., ix. (1892) pp. 161-8. 
1893. 
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