600 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
A and B together, add 10 grm. (1 per cent.) dried pepton and 5 grin. 
(0 • 5 per cent.) salt, boil for 3 minutes, neutralise, and filter. The pro- 
duct is an absolutely clear jelly, which never forms any precipitate. 
The filtration takes 10—12 minutes through an ordinary filter-paper. 
Solution B should not he added to A until cool enough to avoid coagu- 
lation. 
Treatment of Celloidin Sections Stained with Orcein.* — Herr H. 
Jordan takes the celloidin-sections (80—96 per cent.), and by means of 
tissue paper places them on the slide already smeared with albumen or 
albumen-glycerin. The paper is firmly smoothed down, and on the top 
of it is placed another slide. The slides, firmly held in the hand, are 
then heated to coagulate the albumen. When this is effected, the whole 
is immersed in 96 per cent, alcohol, and the upper slide and paper 
removed. The preparation is then transferred to the solvent. The 
solvents recommended are a mixture of equal parts of absolute alcohol 
and ether or acetic ether. The latter may be used before or after 
staining, as it does not damage the orcein. 
Modification of the Weigert-Pal Method for Paraffin Sections.f — 
Dr. E. E. Laslett recommends the following procedure as efficient and 
trustworthy. The material, spinal cord, medulla, &c., is hardened for 
about a fortnight in Muller’s fluid, and then cut into slices not more than 
2 mm. thick. These are placed in Marchi’s fluid for a week, washed, 
and imbedded in paraffin. The sections are fixed to the slide by the 
water method, and then, after removal of the paraffin, placed in the acetic 
acid-hsematoxylin over-night, preferably in a warm oven, as thereby the 
staining process is materially hastened. After washing they may be 
passed into a saturated solution of sodium orlithium carbonate, by which 
the colour is changed to a bluish black. They are then differentiated 
by the Pal method, care being taken not to over-decolorise. The 
advantages of this method are, firstly, that it is a combination of the 
Marchi and Weigert methods, and secondly, that the sections are much 
thinner than by the celloidin method. 
Method of Demonstrating the Structure of Yeast-Cells. J — In 
their investigations on the yeast-cells, Prof. F. A. Janssens and M. A. 
Leblanc used Moeller’s iodine fluid for fixing, and alcohol at 95° for 
hardening. The iodine solution consists of distilled water 100 ccm., 
iodide of potassium 1 grm., iodine to saturation. A few drops of the 
iodine solution are placed on a slide, and a loopful of yeast culture 
carefully mixed with it. Some of the mixture is then carefully spread 
on cover-glasses. When the fluid has evaporated, the cover-glasses are 
transferred to fresh Moeller’s solution for 24 hours. Then, after having 
been washed in water, they are passed successively through one-third 
alcohol, alcohol at 80°, and finally at 95° for at least two days. It is 
necessary to remove all traces of iodine. Several methods were used for 
staining the preparations, among the best being the following : — fuchsin 
4 grm., phenol 10 ccm., alcohol 40 ccm., water 200 ccm. The prepara- 
tions are decolorised with weak H 2 SOI, and contrast-stained with 
Loeffler’s methylen-blue. The method which gave the best results con- 
* Zeitschr. f. wiss. Mikr., xv. (1898) pp. 53-5. f Lancet, 1898, ii. pp. 321-2. 
% La Cellule, xiv. (1898) pp. 203-9. Cf. ante , p. 570. 
