252 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
violet to a mixture of two parts of distilled water and one of acetic acid. 
If a drop of this mixture is added to the preparation containing the 
pollen-cells, the nuclei will almost instantly be coloured a deep blue- 
purple, while the cell-protoplasm remains colourless and entirely uncon- 
tracted. The staining fluid may now be removed by blotting-paper, and 
the preparation mounted in dilute glycerin. Specimens prepared in 
this way, especially when first made, show all the finest details of the 
structure of the nucleus. 
Fixing the Spores of Hymenomycetes.* * * § — Inasmuch as a solution of 
Canada balsam in turpentine-oil has a tendency to oxidize and become 
cloudy after having been prepared for a year, Prof. C. O. Harz now 
proposes to substitute lavender-oil or petroleum for the turpentine-oil. 
Direct Impressions of Plants.f — M. Bertot obtains direct impres- 
sions of plants in the following way : — The plant is first saturated with 
oil by placing between pieces of paper soaked in oil, and an impression 
of it is then obtained in oil on white paper. The paper is now treated 
with graphite, and the oily places are thus turned black and a perfect 
impression of the plant obtained. The paper is now freed from excess 
of graphite by wood-ash. To fix the image, powdered colophone is 
mixed with the graphite, which sinks into the paper when slightly 
warmed. Spots which sometimes appear upon the paper may be removed 
by soaking the paper in an aqueous solution of tragacanth. 
Demonstrating Tubercle Bacilli. J — Dr. Bliesener recommends the 
following method as being very expeditious : — The cover-glass, having 
been dried in the air and passed thrice through a flame, is placed with 
the sputum layer uppermost on a metal plate about 5-6 cm. square fixed 
to a stand so as to keep it horizontal. Five or six drops of carbolic 
fuchsin are then droj)ped on with a pipette and the metal plate warmed 
until the fluid begins to evaporate. The flame is then removed, and 
then the cover-glass, after remaining on the plate for about a minute, 
is washed with water previous to its being dropped on the acid contrast 
fluid (methylen-blue 1*6, H 2 O 100, H 2 SO 4 25). In about fifty seconds 
it is removed, washed in water, and examined. 
The foregoing staining procedure, if combined with Biedert’s method 
of examining sputum, is said by the author to be very satisfactory. 
Biedert’s method consists in boiling the sputa with water to which some 
drops of caustic soda have been added. 
Agar-agar as a Fixative for Microscopical Sections.§ — M. A. Gervis, 
who recommends agar-agar as a medium for fixing sections, imbedded in 
paraffin, on slides, proceeds as follows : — Half a gramme of agar having 
been cut up into small pieces, is allowed to soak for some hours in 
500 grammes of distilled water. When it has swelled up it is boiled 
for about a quarter of an hour in order to completely dissolve the agar. 
* SB. Bot. Ver. Munclien, Nov. 11, 1889. See Bot. Centralbl., xl. (1889) p. 345. 
Cf. this Journal, 1889, p. 461. 
t Bull. Soc. Linn. Normandie, ii., 1887-8 (1889) pp. 442-5. See Bot. Centralbl., 
xl. (1889) p. 285. 
X Deutsche militararztl. Zeitschr., xviii., pp. 406-9. Cf. Centralbl. f. Bakteriol. 
u. Parasitenk., vii. (1890) pp, 72-3. 
§ Bull. Soc. Beige de Microscopic, xv. (1889) pp. 72-5, 
