ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
265 
1891. On the Structure of certain Diatom-valves as shown by 
sections of charged specimens, pp. 441-2, plato VIII. 
1893. On an Endophytic Parasite of Diatoms, pp. 1-4, plate I. 
B. Technique.* 
Hints in Bacteriological Technique.! — For examining bacteria in 
hanging drops, Prof. J. Marek instead of using a cover-glass run round 
with va selin, paraffin, or the like, takes a hollow-ground or plane slide 
and sticks on with cedar oil a plate of black “ patent-gum.” The gum 
plate is about 1 mm. thick, and a circular hole with diameter 8-10 mm. 
is cut out of the middle. In the hollow is placed a droplet of water, 
and the cover-glass with hanging-drop put over. The cover-glass is 
then covered with a slide from which a circle with a diameter of 16-20 
mm. has been cut out. The whole is held together by rubber rings 
and then examined under the Microscope, or it may be held together and 
kept in position by means of the stage clips. 
For simultaneously staining many preparations of bacteria, a modifi- 
cation of the method suggested by Kutner and Troster is advised. On a 
piece of plate glass 6 by 12 cm. and about 1 mm. thick are scratched 
vertical and horizontal lines at a distance of about 6 mm. apart. From 
the same kind of glass are cut four strips, 6 and 10 *8 cm. long and 
about 6 mm. broad. Two of each of these strips are well smeared with 
soluble glass, and having been accurately adapted to the edges of the 
plate and with moderate pressure, are allowed to dry for some hours and 
then incubated for half an hour at 120°~150°. When cold the inner 
edges of the strips are smeared with soluble glass, and the drying and 
heating repeated. When cold the plate can be used as a slide. The 
bacteria are fixed by heating the slide for 5-10 minutes to 120°-130°, 
and then the stain is poured on into the slide-pan, the rest of the 
manipulation being as usual. 
By enlarging the size of the glass plate and the strips to be fixed on 
a capsule can be made for the cultivation and examination of micro- 
organisms which possesses advantages over those of Petri, Soyka, and 
others. The glass plate should be 12 by 16 cm., and about 1-1*15 mm. 
thick ; of these plates two are required, one serving as the lid. The strips, 
eight in number, are 8 and 13 * 2 cm. long. A capsule having a super- 
ficial area of 96 ccm. is thus formed and is especially convenient for 
photographic and enumeration purposes. 
Doubt as to whether a certain colony has been inoculated from or 
not may be avoided by the use of a chart subdivided into definite areas 
by vertical and horizontal lines. The chart is placed underneath the 
capsule or plate, the position of the colony noted and then registered. 
A moist chamber for plates or double capsules is conveniently made 
with a large glass rectangular pneumatic trough, the edge of which is 
protected with cotton-wool and covered with a glass plate larger than the 
* This subdivision contains (1) Collecting Objeots, 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. 
f Centralbl. f. Bakteriol. u, Parasitenk., xv. (1894) pp. 112-4. 
1894 
T 
