ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
537 
parations, which he has found useful in the examination of chromato- 
phores, crystalloids, and various cytoplasmic elements. 
(1) Picro-fuchsin stain. — The sections are fixed to the slide, and the 
paraffin and its solvent xylol having been removed, are placed in a 
solution of acid-fuchsin, which is made by dissolving 20 grm. of the 
pigment in 100 ccm. of anilin water. In this solution, which should be 
gently warmed, the sections remain for 2-5 minutes, and are then washed 
in a mixture of 1 part of a saturated alcoholic solution of picric acid and 
2 parts of water until no more dye is given off. After this the picric 
acid is to be extracted in absolute alcohol ; then the sections are passed 
through xylol and mounted in xylol balsam. 
(2) Acid-fuchsin staining, with subsequent washing out in flowing 
water. — This method is serviceable for staining thick sections made 
from living tissue and then fixed. After the fixative is extracted the 
sections are placed in a 0 • 2 per cent, watery solution of acid-fuchsin, in 
which they remain for 24 hours or longer. The excess of stain is 
then extracted in flowing water, and this is best done by means of 
Steinach’s glass filter capsules.* The capsules are placed in a receiver, 
over which is a pipe with a number of small taps, from which the water 
can be made to flow into the capsules. In adopting this method it is 
advisable to manipulate a large number of sections at once, and to 
examine them from time to time to ascertain the proper degree of 
decoloration. 
(3) Iodine-green for staining chromatophores. — The sections are 
made from tissue previously fixed with an alcoholic sublimate solution, 
and then immersed for half an hour in a saturated aqueous solution of 
iodine-green. They are then washed in water and examined in glycerin 
or Hoyer’s mounting fluid, or in balsam. If balsam be used, then 
dehydration must be effected by merely drying the preparation. Then 
xylol is added, and, when saturated with this, the xylol balsam. As a 
contrast stain for the rest of the tissue, a watery solution of Bismarck 
brown may be used. 
(4) Ainmonia-fuchsin for staining the chromatophores. — This stain 
is prepared by adding chemically pure ammonia to an alcoholic solution 
of fuchsin until the fluid assumes a bright yellow colour. The solution 
may be used at once, but will only keep a few weeks. The sections are 
fixed to a slide and some of the solution poured thereon and allowed to 
remain for some few minutes. They are then washed and examined in 
water or glycerin. Hoyer’s mounting medium may be used, or even 
balsam. If the latter, then the sections must be dehydrated by drying 
them in the air. 
Staining Human Retina with Acid Hsematoxylin-t — Dr. J. Schaf- 
fer has been able to differentiate the outer and inner segments of the rod 
and cone layer of human retina by sta'ning the tissue with the acid 
logwood recommended by Kultschitzky. 
The sections, imbedded in celloidin, are taken from the Muller’s 
fluid or alcohol in which they have been fixed and hardened, and left 
during the night in a 1 per cent, solution of chromic acid, which acts as 
* This Journal, 1888, p. 850. 
t SB. K.K. Akad. Wiss. Wien, xcix. (1890) pp. 110-20 (1 pi.). 
1890. 2 p 
