448 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
washer. 25,1b. of air-pressure suffices to filter a litre of agar-agar in ten 
minutes, and tlie usual clarification with white of egg is unnecessary. 
Modification of the Celloidin Series Method. — Prof. F. Dimmer * * * § 
uses a gelatin solution instead of the sugar solution. Some 16 grm. of 
gelatin are dissolved in 300 grm. of warm water. This solution is then 
poured over large glass plates, previously warmed and placed in a nearly 
horizontal position. The thin films, protected from the dust, dry in about 
two days. The sections are removed from the knife in the usual way 
and placed on the gelatin plates and kept moist with 70 per cent, alcohol. 
When a plate is full of sections the excess of alcohol is removed by 
covering the surface with a piece of closet-paper and pressing out the 
fluid. The sections are then covered with photoxylin solution (photo- 
xylin 6, absolute alcohol and ether d a 100 ccm.). When this is about 
dry, the plate is immersed in water at 50°-55° C. When the plates are 
set free from the glass, they are easily picked up on closet-paper and 
transferred to a staining or clarifying fluid. 
The modification devised by Mr. J. S. Kingsley | consists in harden- 
ing the collodion-saturated mass in chloroform, and when firm placing 
the block in a mixture of 1 part carbolic acid and 3 parts xylol. The 
sections are cut with a razor flooded with the xylol- carbolic acid, trans- 
ferred to a slide, and mounted directly in balsam. 
Bacteriological Notes.J — (1) Herr London has found that if cover- 
glass preparations of the cholera vibrio be treated with a mixture com- 
posed of 1 part of an alcoholic solution of picric acid and 2 parts of 
water for one minute, and then washed in water for 15 minutes, the 
cholera vibrios are stained by the picric acid. All other bacteria are 
decolorised. 
(2) The above-mentioned picric acid solution may be substituted for 
the iodopotassic iodide solution in Gram’s method. 
(3) Clove-oil water is better than anilin-oil water for making 
Ehrlich’s fuchsin solution. There is no precipitate, and in the dark the 
fuchsin solution will keep for two months. 
(4) A 1 per cent, solution of thionin stains the tissues blue and 
the bacteria violet. Hence this metachromatism may be made use of 
with advantage for staining bacteria in tissues. 
(5) The author recommends the use of karagen plates made like 
gelatin plates for the culture of Amoebae. 
Use of Acetone in Histology.§ — Dr. P. A. Fish states that the 
action of acetone on pyroxylin is more intense than that of the ether- 
alcohol mixture used for dissolving celloidin. It is also a fixing, 
hardening, and dehydrating agent. Hence it may be used as follows : — 
Fix in 70 per cent, acetone ; dehydrate in strong acetone ; soak in 4 per 
cent, acetone-collodion ; then in 8 per cent, acetone-collodion. 
New Nissl Method. j| — Dr. J. R. Lord makes sections of fresh tissue 
with a freezing microtome, and fixes the sections in the follow ing solu- 
* Zeitschr. f. wiss. Mikr., xvi. (1899) pp. 41-6. 
t Journ. Applied Microscopy, ii. (1899) p. 325. 
j Arch. Biol. Wissensch. St. Petersburg, 1898, p. 319. See Centralbl. Bakt. u. 
Par., l te Abt. xxv. (1899), p. 839. 
§ Journ. Applied Microscopy, ii. (1899) pp. 322-4. 
|| Journ. Mental Science, xliv. (1898) pp. 693-700 (1 pi.). 
