816 SUMMARY OF CURRENT RESEARCHES RELATING TO 
them covered over (they must never be exposed to light for more than a 
few seconds) for a few minutes. 
(d) Put some 1 per cent.. formic acid in a watch-glass, float the glass 
in hot water, put the sections in the acid, cover them over, and keep 
them in the dark and fairly hot until they turn crimson. This generally 
takes about an hour, but the operator must be guided by the tint of the 
sections, which he must look at from time to time. A simple way to 
do this is to fill an old china anchovy paste-pot with hot water, place it 
on a stove, float the watch-glass containing the acid and the sections in 
it, and cover it up with its own lid. 
(e) When stained, immerse the sections in cold distilled water for 
about half an hour. 
(/) Dry sections and mount them in glycerin-jelly. Avoid Canada 
balsam. I have always found specimens mounted in Canada balsam go 
wrong. The bottle of gold chloride must always be carefully kept in 
the dark. 
I have found this method very successful and very easy ; moreover, 
I have many sections now in my possession which are quite eight years 
old and have not faded in the slightest degree.” 
Vital Reaction of Methylen-blue.* — Herr H. Kuhn obtained specially 
purified methylen-blue for injecting into the dorsal lymph-sac of frogs. 
The reaction was obtained in about thirty-six hours by injecting every 
twelve hours one ccm. or three ccm. all at once of the strong solution. 
When the animals were opened no effect was visible, but after five 
to ten minutes, all the organs, especially liver and kidneys, became blue 
from exposure to the air. 
The preparations do not keep long, so they are useless as permanent 
microscopical preparations. 
Influence of Colouring Matters on Spermatozoa. f — Dr. Emma 
Leclercq gives the following tabular statement as to the effects of various 
reagents on spermatozoa. 
Colouring Matter. 
Results. 
On Nucleus. 
On Accessory 
Corpuscle. 
Carmine alone (Frenzel) 
,, „ (Flemming) .. 
Renault’s hmmatoxylin 
Ranvier’s picrocarmine 
Ehrlich’s violet and eosin 
„ „ and carmine 
Picrocarmine and methyl-green 
Light carmine 
Rose 
Violet 
Rose 
Violet 
Violet 
Violet 
(The spermato: 
Pale rose 
Red 
Deep violet 
Orange 
Rose 
Rose 
Carmine yellow 
zoa being green) 
Preparing Nerves stained by the Vital Methylen-blue Method.! 
— Herr B. Feist injects frogs with three or four ccm. of a strong solution 
* Arch f. Anat. u. Entwickelungsgesch., 1890, pp. 113-5. Cf. Zeitschr. f. Wiss. 
Mikr., vii. (1890) pp. 230-1. t Bull. Acad. Roy. Belg., lx. (1890) p. 138. 
X Arch. f. Anat. u. Entwickelungsgesch., 1890, pp. 116-84 (2 pis.). Cf. Zeitschr 
f. Wiss. Mikr., vii. (1890) pp. 231-4. 
