ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
125 
makes very fine sections of pieces which have been for some months in 
Muller’s fluid ; after putting them in 90 per cent, alcohol he washes 
them lightly with water to get rid of the alcohol. They are then im- 
mersed for from 5 to 15 minutes in a 1/500 or 1/1000 solution of osmic 
acid, washed in water, and then immersed in a solution of 5 per cent, or 
10 per cent, tannin, and heated to 50° to 55 ° ; after about 5 minutes they 
may be washed several times in water, have a double stain or carmine or 
watery solution, and be mounted in the usual way. 
The sections thus treated are brown or black in the white substance, 
and grey in the grey ; it is only the myelin that is stained. An advan- 
tage of this method is that, the coloration not being diffused as by the 
Weigert or Weigert-Pal method, the fine structure of the fibres can be 
studied. 
The sections should be thin ; if they are too thick they should, after 
the final washing in water, be decolorized by Pal’s method. 
Another method is to take fine sections from the alcohol in which 
they have been lying and to wash them lightly with water, put them 
in a warm bath of 5 or 10 per cent, tannin for 3 to 10 minutes, wash 
in water, decolorize or not, wash for a long time in water, double stain 
or not, and mount in the ordinary way. This method is simple, rapid,, 
safe, and cheap. Could more be demanded of it ? 
Staining of Centrosomes.* — Herr G. Karsten states that the same 
staining reagents are not applicable for bringing out the directing 
spheres (centrosomes) in the case of plants as of animals. No one 
reagent has been found to answer in all cases. The best results were ob- 
tained by the following method of treating vegetable cells : — The material 
was fixed either by a mixture of 0*5 gr. chromic acid and 0'2 gr. 
osmic acid in 100 of water, or by one of 0*5 gr. platinum bichloride 
and 0-5 gr. chromic acid in 100 of water, or by absolute alcohol. 
The staining reagent used was a mixture of Weigert’s acid fuchsin and 
Grubler’s methyl-green 0*0. After allowing a sufficient period, the 
centrospheres and protoplasm are coloured red or rose, while the nuclear 
chromosomes retain their green colour even after washing with absolute 
alcohol. Coccinin may also be used with advantage for staining the 
protoplasm and the centrospheres. 
Staining Reaction of Sputum.t — Dr. C. Zenoni, not being satisfied 
with Schmidt’s method for the differential diagnosis of pneumonia and 
bronchitis, adopted a saturated solution of safranin instead of the Biondi 
triple stain, which imparted to mucoid bronchitic sputum a greenish-blue 
hue, and to the pneumonic a red, tending to violet. With the safranin 
the mucoid elements are stained sulphur yellow to brownish yellow, the 
albuminous red or reddish yellow. The cover-glass preparations are 
first fixed for 1/4 hour in alcohol, and then stained with a semi-saturated 
solution of safranin. Leyden’s spirals showed a difference of colour in 
the central and outer parts of the spiral. According to the author, the 
method is very good for making a differential diagnosis between bron- 
chitic and pneumonic sputum, even on macroscopic examination. 
* Journ. de Bot. (Morot), viii. (1894) p. 245. 
t Centralbl. f. wiss. Med., xv. (1894) p. 257. See Centralbl. f. Bakteriol. u. 
Parasitenk., xvi. (1894) p. 667. 
