248 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
tion of ferrous sulphate, then wash, place for the same length of time 
in a 5 per cent, aqueous solution of tannin, wash again, again cover with 
the iron solution, and leave for a minute or two, or until they change 
to a rather dark colour. After washing off the iron, stain with anilin- 
safranin (1 part 1 per cent, alcoholic solution of safranin and 2 parts 
water) from 30 minutes to 1 hour, and then 15 minutes or more in an 
aqueous solution of picro-nigrosin long enough to take a dark bluish- 
green colour. Then raise through the grades of alcohol, and mount in 
Canada balsam. The centrosomes are by this process stained very dark ; 
— and the attraction-spheres are well defined, often showing the radiate 
structure. 
Flagella-Staining.* — Dr. R. Bunge has improved his method of 
staining flagella in the following manner. j After filtering a requisite 
quantity of the mordant, which should be a few days old, into a test- 
tube, peroxide of hydrogen is added, drop by drop, until the mordant 
becomes of a red-brown hue. It is then shaken up and filtered over the 
prepared cover-glass, on which it is allowed to act for about 1 minute. 
The cover-glass is then mopped up, dried, and stained, preferably with 
carbol-gentian. The flagella seem swollen and are so deeply stained 
that this can never be overlooked. Besides staining the flagella the 
capsules are also simultaneously coloured by this method. 
Lithium Bichromate as a new Reagent for Hardening Adult 
Brains. t — Mr. 0. S. Strong reports on the use of this reagent in the 
application of Golgi’s method. As is well known, the principal defects 
of this method are the uncertainty of good results, inequality of the 
impregnation, and the expense in the use of so much osmic acid. It 
occurred to Mr. Strong that the defects could be remedied to some extent 
by enhancing the penetration of the silver nitrate. This was attained 
by mixing the silver nitrate solution with solutions of sodium or zinc 
sulphate. In certain cases this modification gave very good results, but 
further experience is necessary to determine its exact value. Lithium 
bichromate, however, promises to prove valuable in certain lines of 
work. The long Golgi’s method dispenses with the osmic acid, and 
therefore with the expense, but the period of time is so long that it 
would be an advantage to be able to shorten it. This time may be 
reduced from the 20 or 30 days now required to 1 to 3 days, by simply 
using lithium bichromate instead of potassium bichromate. The tissue 
should be cut into small pieces, and put into a liberal supply of a 
2 to 3 per cent, solution of lithium bichromate. In the course of 1 to 2 
days pieces should be placed in the silver nitrate solution at intervals. 
A piece found to be impregnated may be washed with strong alcohol for 
about half-an-hour, stuck on a microtome block, and cut in 95 per cent, 
alcohol into sections of suitable thickness. After being washed in 
95 per cent, alcohol, these may be cleared in 01. origanum cretici, rinsed 
in xylol and mounted in dammar-balsam without a cover-slip. For the 
human brain and for that of the hen, it has been found that this method 
* Fortschr. d. Med., xii. (1894) No. 24. See Centralbl. f. Batteriol. u. Para- 
sitenk., l e Abt., xvii. (1895) pp. 102-3. 
f See this Journal, 1894, p. 640 ; 1895, p. 129. 
X Trans. New York Acad. Sci., xiii. (1894) pp. 237-9. 
