ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
453 
100 ccm., formol 10 percent, aqueous solution 20 ccm. If used for stain- 
ing blood, the blood is smeared on the slide with a strip of paper. It is 
dried in the air, and the solution is then dropped on. After 2 minutes 
the excess of staining solution is poured off, and on the still damp pre- 
paration is dropped methylen-blue F.B. After another two minutes the 
preparation is thoroughly washed with water, dried, and mounted in 
balsam. 
(3) Methylen-blue F.B. — -Methylen-blue saturated aqueous solution 
1 part ; formol 4 per cent, aqueous solution 1 part. When staining pus 
or gonococci in urine, the air-dried film is first treated with eosin F., 
and after two minutes is thoroughly washed with water. It is then 
treated for 30 seconds with an aqueous saturated solution of methylen- 
blue diluted before use in the proportion of 1-3. The preparation is 
then carefully washed with water. 
For staining by Gram’s method, gentian-violet F. is used. — Gentian- 
violet 10 per cent, alcoholic solution 10 ccm. ; formol 2 * 5 per cent, aqueous 
solution 100 ccm. The preparation is first treated with the gentian- 
violet F. solution for 5 minutes, and then with the iodopotassic iodide 
solution for 2 minutes. This is followed by decolorising in 10 per 
cent, alcoholic solution of aceton. After having been washed in water, 
the preparation is contrast stained with Bismarck-brown for 30 seconds. 
It is again washed in water, and dried. 
Staining Solutions made with Pyroligneous Acid.* — Herr E. 
Burchardt gives the following formulae for staining solutions containing 
pyroligneous acid : — 
(1) Pyroligneous acid haematoxylin. —Pyroligneous acid 130*0 parts ; 
potash alum 2*0; haematoxylin 0 * 5. The alum is first dissolved in the 
pyroligneous acid, and then the haematoxylin dissolved in strong spirit 
is added. After exposure to light for 12 days the solution is ready for 
use. It is a permanent stain, but the staining power decreases with 
lapse of time. The strength of the solution may, however, be restored 
by the addition of a little pyroligneous acid. The solution is useful for 
staining either in mass or in section. The pieces or sections are to be 
transferred directly from alcohol to the stain, wherein they remain 
for 12 hours or longer, according to their size. On removal they are 
thoroughly washed in 50 per cent, alcohol, and then treated in the 
ordinary way. 
(2) Pyroligneous acid carmine. — Carmine Xr : pyroligneous acid 
100 parts ; carmine 2. The mixture is to be heated slowly over a small 
flame, evaporated down to one-half, and filtered when cold. The pieces 
to be stained are immersed in the solution for 12-24 hours, and then 
washed in 50 per cent, alcohol. Next they are differentiated in alum- 
alcohol (50 per cent, alcohol saturated with alum). This takes 2 or 
3 days ; after this they are washed in 50 per cent, spirit, and treated 
in the usual way. 
Carmine Pr. : Pyroligneous acid 100 parts ; carmine 3 ; potash-alum 
0*5. Evaporate down to one-half, and filter when cold. Stain for 
2-24 hours, and wash in 50 per cent, alcohol. 
Carmine Xr+Pr (double carmine) : Mix equal bulks of the foregoing. 
* Arch. f. Mikr. Anat., liii. (1898) pp. 232-7. See Zeitschr. f. wiss. Mikr., xv. 
(1899) pp. 453-5. 
1899 2 H 
