ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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The cover-glass preparation, dried in air, is covered with 2 per cent, 
aqueous gentian- violet solution, and warmed until it begins to vaporize ; 
after this it is washed in water, and next treated with 2 per cent, acetic 
acid for 6-10 seconds, and then washed in water again. 
New Staining Process.* — Dr. 0. Zacharias recommends the follow- 
ing process for both animal and vegetable preparations. The material is 
laid in 70 per cent, alcohol, and then, for from 16 to 54 hours, in acetic- 
earmine, prepared by boiling 1 gr. powdered carmine for 20 minutes in 
150-200 gr. dilute acetic acid, and filtering when it has become cold. 
The preparation is washed in dilute acetic acid, and then placed for 
from 2-3 hours in ferric-oxide-ammonium-citrate. 
Staining and Fixing of Diatoms. t — Dr. P. Miquel finds the staining 
reagent best adapted for demonstrating the gelatinous envelope of 
diatoms to be an aqueous or boric solution of methylen-blue, which is 
not taken up so readily by the gelatinous stipe. The same reagent, 
especially in a slightly ammoniacal solution, may be used for demon- 
strating the nucleus, which is stained blue, while other substances con- 
tained in the cell take from it a dark blue -violet stain. For fixing, the 
author uses a solution of 65 gr. corrosive sublimate and 15 gr. sodium 
chloride in 100 ccm. of water. 
Easy and Rapid Method for Removing Picric Acid from Tissues. if 
— Herr O. Jelinck uses both picric acid alone and in conjunction with 
sublimate as a fixative. In the first case it is a saturated aqueous solu- 
tion, in the latter it is a saturated aqueous solution of picric acid with 
an equal bulk of a saturated solution of sublimate in physiological salt 
solution. The piece of tissue should be very small, and immersed in 
30-50 times its bulk of fluid for 1-24 hours. To 100 cCm. of the 
fluid it is often useful to add 5 ccm. of acetic or formic acid. When 
properly fixed the pieces are to be transferred to alcohol, the strength of 
which must be gradually increased until absolute alcohol is reached. 
The pieces should be often moved about and the alcohol frequently 
renewed. By transferring the sections (celloidin sections) to a saturated 
solution of carbonate of lithia the picric acid is easily dissolved out. 
Afterwards they are washed in distilled water and stained in the usual 
way with hsematoxylin or other dyes. 
By a similar process picric acid may be removed from comparatively 
large pieces. In this case it is best to proceed as follows : — To a satu- 
rated aqueous solution of lithium carbonate add a few drops of 95 per 
cent, alcohol until a faint white precipitate falls. In this turbid fluid 
immerse the object to be fixed. Then keep on adding to the fluid, which 
has now become clear, solution of lithium carbonate until the precipitate 
no longer dissolves, and alcohol, which of course must be frequently 
changed so long as the yellow colour shows itself. The tissue or piece 
then appears white, just as if it had been fixed in sublimate. Last of 
all transfer it to 95 per cent, spirit to free it from the last traces of 
lithia, and thereupon treat in the usual way. 
* Forschungsber. Biol. Stat. Plon (Zacharias) Pts. 1, 2, 1893, 94. See Bot. 
Centralbl., lx. (1894) p. 137. f Le Diatomiste, ii. (1894) pp. 107, 112. ■ 
X Zeitschr. f. wiss. Mikr., xi. (1894) pp. 342-6. 
