ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
543 
acetylene burner on a heavy lens-stand for convenient up-and-down 
adjustment ; but other light-sources can of course be used. 
The arrangements for adjusting and focussing the apparatus are of 
the usual character, and are described in full by the author. 
Light of any required refrangibility can finally be received on the 
objective of the Microscope. The author claims that the advantage of 
being able to work with any part of the spectrum outweighs the laborious- 
ness of fitting up the apparatus, which however need occur but once, as 
the positions of the parts could be registered on the scale. 
Schroeder, Dr. Hugo — U eber Beleuchtungsprobleme. (On illumination pro- 
blems.) 
[A series of discursive articles.] 
Central-Ztg. f. Optilc u. Mechanik , 1899, Nos. 2-7, Jan. 15 to April 1. 
(4) Photomicrography. 
Marktanner-Turneretscher, Gottlieb, F.R.M.S — Fortschritte aus dem 
Gebiete der Mikrophotographie. (Progress in the department of photomicro- 
graphy.) 
[This is the publication in pamphlet form of a section of Dr. J. M. Eder’s 
‘ Jahrbuch fur Photographie und Reproductionstecbnik flir 1899.’ The author 
has compiled an illustrative descriptive list of the various instruments, 
books, &c., on the subject issued during the last two years. The list is 
cosmopolitan, and most of the items have been noticed in our Journal.] 
■Sobotta, Dr. J., of Wurzburg— Ueber die Verwertung von Mikrophotographien 
fur die Untersuchung und Reproduktion mikroskopischer und embryologischer 
Praparate. (On the value of photomicrographs for the examination and repro- 
duction of microscopical and embryological preparations.) 
[In two chapters : (i.) The photomicrography of preparations of the central 
nervous system with Weigert’s boundary colours; (ii.) The photomicro- 
graphy of opaque objects.] Munich, 1899, 34 pp. and 1 pi. 
(6) Miscellaneous. 
Babes, V. — Bemerkungen iiber demonstrative Vortrage und liber Projectionstech- 
nik. (Observations on proposed methods of demonstration and on projection 
technique.) 
Centralb.f. allgem. Pathol, und pathol. Anat., Bd. X. (1899) No. 6, p. 233. 
B. Technique.* 
(1) Collecting- Objects, including- Culture Processes. 
Preparing Agar.j — Mr. W. W. Alleger gives the following method 
for preparing agar. Rub up 10 grm. of powdered agar and Witte’s 
powdered pepton and 5 grm. of sodium chloride in a porcelain saucepan 
with water sufficient to form a thin paste. Add gradually, while stirring 
the mixture, 500 ccm. of water, and then heat until the agar is dissolved. 
To the juice from 500 grm. of lean meat add 500 ccm. of water, and • 
then mix with the agar solution, which, while hot enough to remain 
fluid, should have cooled sufficiently not to coagulate the albumen in 
the meat-water. Neutralise with 4 per cent, of caustic soda ; boil the 
mixture until all the albumen has coagulated, and then, if necessary, 
correct the reaction and fill up with boiling water, after which filter 
* This subdivision contains (1) Collecting Objects, including Culture Pro- 
cesses; (2) Preparing Objects; (3) Cutting, including Imbedding and Microtomes; 
(4) Staining and Injecting ; (5) Mounting, including slides, preservative fluids, &c. ; 
<6) Miscellaneous. t Trans. Amer. Micr. Sue., xx. (1899) pp. 91-5. 
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