ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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Flemming’s solution or osmic acid, washed in water for at least twenty- 
four hours afterwards, and then hardened in the usual way with alcohol. 
The pieces were imbedded in paraffin, after the Naples method, before 
cutting. Biondi’s reagent, as prepared by Griibler of Leipzig, proved 
by far the most valuable stain for cancers hardened in alcohol ; one 
gramme of the powder is dissolved in 80 ccm. of water, and 15 ccm. of a 
5 per cent, solution of acid fuchsin is added to it. In a footnote the 
authors add that Griibler now advises a *4 per cent, solution of the 
powder with the addition of 7 ccm. of a • 5 per cent, solution of acid fuch- 
sin to 100 ccm. of the first solution. The sections, after remaining in 
this solution for an hour at least, are washed in water (30 seconds), and 
passed through 95 per cent, alcohol (1 minute), absolute alcohol (2-5 
minutes), xylol (2-15 minutes), and finally mounted in Canada balsam 
dissolved in xylol. 
The only drawback to such preparations is that the colour has a ten- 
dency to fade ; they are, however, very beautiful and instructive. The 
nucleus of the cell is green, the nucleolus reddish-brown or red, and the 
protoplasm orange-red. On the other hand, the nucleus of the parasite 
is red, and the protoplasm a light Cambridge blue colour. After using 
Flemming’s solution, Biondi’s reagent may also be used. 
Solutions of hsematoxylin ani Gerrard’s logwood-stain give very fair 
results, after fixing with osmic acid or Flemming’s solution ; better pre- 
parations are obtained by combining Gerrard’s logwood stain with a 
solution of eosin, or with a *5 per cent, of rose-bengale in 80 parts of 
water and 20 parts of absolute alcohol. 
Use of Centrifugal Machines in Analytical and Microscopical 
Work.* — Herr W. Thorner recommends the use of a centrifugal machine 
for the separation of solid or fluid bodies suspended in liquids which only 
settle very slowly under ordinary conditions. The apparatus is set in 
rapid rotation either by a crank, toothed wheels, or a small turbine. 
The vessel containing the liquids is attached to the upper part of the 
apparatus in such a way that during the rotation it takes the horizontal 
position, and at the end returns by steady oscillations to the vertical. The 
liquids to be separated can also be brought into small glass receptacles 
fitted into a metal holder which is attached to the plate of the machine. 
According as the material to be estimated sinks or floats, these recep- 
tacles are narrowed in their lower or upper part, and there provided 
with a scale. 
The author has modified the Victoria centrifugal machine, which he 
lias used in his experiments, by the addition of an iron jacket provided 
with a cover. By this means the enclosed air shares in the rotation and 
the air resistance is avoided. 
Aid to Microscopical Examination of Faeces.] — Dr. Herz uses the 
centrifuge for separating the different constituents of the faeces. The 
stools are diluted with water, and after centrifuging, separate into layers, 
the uppermost consisting of bacteria, thin masses of undigested cellulose, 
striated muscle, thin layers of round cells, clostridium, starch, &c. 
* Zeitschr. f. Instrumentenk., xii. (1892) pp. 390-1. See Chem. Ztg, xvi 
p. 1101 . 
t Centralbl. f. Klin. Med., 1892, No. 92. See Centralbl. f. Bakteriol. u. Para- 
siteiik., xii. (1892) p. 769. 
