THE MICROSCOPE. 27 
Fig. 1. The Section Flattener attached to a section knife: 
(a) Blade of the section knife; (4) Tang; (b) Section Flattener; 
(c) Milled nut; (d) The part of the clamp bearing the hollow cylin- 
der; (e) Part of the clamp; (f) Screw holding the two parts of the 
clamp together. 
Fig. 1, A.—Section showing the manner of hooking the Section 
Flattener over the back of the blade. 
Fig. 1, B and D.—Sections showing the form of the Section 
Flattener and its relation to the cutting edge, except at the ends. 
Fig. 1, C.—Section of the tang of the knife, showing the man- 
ner of attaching the clamp. 
(1) A brief account of this Section Flattener is given in our paper (Serial 
Microscopic Sections) in ‘‘ The Medical Student” for November, 1883, p. 14. 
(2) Since writing this article, our attention has been called to a some- 
what similar device by Andres, Giesbrecht and Mayer (Neuerungen in der 
Schneidetechnic: Mittheil. Zool. Station Neapel, 4 Bd. 3 Hft. (1883) pp. 
429—436. An abstract of this paper is published in the Journal of the Royal 
Microscopical Society for December, 1883, p. g16, and in the December num- 
ber of the American Naturalist, p. 1312. As our device seems simpler and is 
applicable to every form of section knife we thought worth while to give this 
somewhat complete description of it. 
(3) F. E. Schultze. Ein Schnitt Strecker, Zool. Anzeiger, 1883, p. 100. 
THE CORNELL UNIVERSITY, Nov. 15, 1883. 
THE PARABOLA AS AN ILLUMINATOR FOR HOMO- 
GENEOUS IMMERSION OBJECTIVES. 
BY A. Y. MOORE, M. D. 
HAT the illumination of an object is second in importance only 
to the glasses through which it is seen, is a fact well known to 
all practical microscopists; and it is a notable fact that there are 
about as many different forms of sub-stage condensers as there are 
objectives. By looking through the various catalogues of micros- 
copes and accessory apparatus it will be seen that a great many im— 
mersion achromatic condensers are offered for sale, to many of 
which a price is attached whose figures are positively forbidding to 
their purchase by the majority. 
Although many of these wide angled condensers are claimed 
to bring out the full capabilities of the more recent homogeneous 
