ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
393 
or palladiridiura, and better still, that the whole objective and even the 
whole instrument should be protected from the deleterious effect of 
chemical reagents by a similar deposit. 
3) Illuminating and other Apparatus. 
Counting Apparatus specially adapted for Petri’s Capsules.* * * § — 
Dr. F. Lafar has devised a circular counting apparatus in which the 
area of the main sectional divi- 
sions is equal to 1 qcm. Each 
of these six divisions has an 
angle of 60° and these are further 
subdivided into smaller compart- 
ments of 20°, so that the whole 
field is in 18 divisions. The 
radii of the circles are 13 *8 mm., 
27*6 mm., 36*6 mm., 43-7 mm., 
and 50 mm. Three of 20° sectors 
are further subdivided by cross 
lines for counting very closely 
set colonies. 
The glass plate in which these 
lines and circles have been etched 
is mounted in a circular frame 
of wood or brass, about 8 mm. 
high and 9*5 cm. in diameter. 
(4) Photomicrography. 
Photomicrography and Projection.! — Dr. R. Neuhauss contributes 
the article on Photomicrography to the Photographic Encyclopaedia pub- 
lished by W. Knapp, of Halle a. S. It is intended especially for those 
who have no time to study the more comprehensive text-books, and yet 
wish to be instructed in the methods which are proposed to obtain useful 
photomicrograms by simple means. 
Simple Photomicrographic Camera. { — Herr S. Engel has con- 
structed a small camera, resting at right angles on three feet, and 
considers that the Francotte camera and all other photomicrographic 
apparatus are greatly inferior to it. Dr. R. Neuhauss, however, states 
that the Engel model does not differ essentially from apparatus which 
saw the light forty or fifty years ago, and that the photomicrograms 
which were taken by Engel with his camera were greatly inferior to 
most of the photomicrograms taken by others with the Francotte camera 
and all other photomicrographic apparatus. 
Stereoscopic Photomicrography.§ — Herr Hansemann describes a 
method for obtaining stereoscopic photomicrograms which is essentially 
* Zeitschr. f. Nahrungsmitteluntersuchung, 1893, p. 429. See Centralbl. f. 
Bakteriol. u. Parasitenk., xv. (1894) pp. 331-3 (1 fig.). 
f Encykl. d. Photographie, W. Knapp, Halle a. S., 1894. See Zeitschr. f. wiss. 
Mikr., xi. (1894) p. 25. 
t Berliner Klin. Wochenschr., 1893, No. 47. See Zeitschr. f. wiss. Mikr., xi. 
(1894) p. 26. 
§ Yerhandl. der Berliner Physiol. Gesellsch., 1892-3; Arch. f. Physiol., 1893, 
H. 1, 2, p. 193. See Zeitschr. f. wiss. Mikr., xi. (1894) p. 26. 
