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SUMMARY OF CURRENT RESEARCHES RELATING TO 
Stain for 6-24 hours, and then soak in 50 per cent, alcohol for 1-12 
hours. Sometimes it is expedient to differentiate in alum-alcohol. 
(3) Pyroligneous acid cochineal. — Pyroligneous acid 100 parts ; 
cochineal 4 ; potash-alum 0 • 5. Boil down to one-half and filter. 
Immerse for 12-24 hours, soak in 50 per cent, alcohol, differentiate 
in alum-alcohol, and proceed as usual. 
Weigert-Pal Staining of very young Brains.* — Herr A. Dolken 
gives the following procedure for staining the brains of very young 
animals by the Weigert-Pal method. Sections of about 50 /x thick (in 
rats and mice they should be not more than 30 /x), are cut, and placed 
for more convenient manipulation on photoxylin plates. They are then 
placed in cold haematoxylin solution (Pal) for 4—5 days, after which 
they are incubated in the staining solution at 37° for 2 hours. When 
cold they are immersed in tap water for 6-8 hours, and then in alkaline 
distilled water (2-3 drops KHO to 1 litre) for a quarter of an hour. 
The sections are next decolorised in permanganate of potash solution, 
about 0 * 5 per cent., until the undeveloped non-medullated areas are just 
beginning to become transparent. After having been well washed in 
distilled water, they are immersed in 1 per cent, oxalic acid solution 
until the non-medullated spots look pale brown, the cortex and nuclei 
being somewhat darker. Thereupon they are washed in distilled water, 
after which the fibres appear dark blue, the cortex and nuclei light 
brown to yellow, the undeveloped non-medullated places pale yellow to 
white. 
The material should be fixed in 5-10 per cent, formaldehyd or in 
ethylaldehyd for 2-4 weeks, and then hardened in bichromate for 5-7 
months. 
New Method of Staining Malaria Parasites.^ — Dr. Futcher and 
Dr. Lazear recommend the following new combination of old methods 
for staining malaria parasites. The dried films are to be fixed in freshly 
made formalin-alcohol (4-5 drops of 10 per cent, formalin to 10 ccm. of 
95 per cent, alcohol). Immerse for 1 minute, then wash in water, blot, 
and dry. Stain for 10-15 seconds in a saturated solution of thionin in 
50 per cent, alcohol, of which 20 ccm. are added to 100 ccm. of 2 per 
cent, carbolic acid. Then wash, blot, dry, and mount in balsam. 
Staining Spinal Cord Cells.J — Mr. E. P. Sargent recommends the 
following procedure for staining the principal elements in the spinal 
cord of Ctenolabrus coeruleus. The material is fixed in 10 per cent, and 
afterwards in 5 per cent, formol. After having been washed in water, 
it is immersed for 24 hours in 5 per cent, solution of copper sulphate. 
It is then sectioned, and the sections, which had been placed on slides, 
are stained for 15-30 minutes in the following mixture : — Phosphor- 
molybdic acid 10 per cent, solution 1 ccm. ; haematoxylin crystals 
1 grm. ; chloral hydrate 10 grm. ; water 400 ccm. 
The preparations are then washed, dehydrated, cleared up, and 
mounted in the usual way. The nerve-fibres, neuroglia, and dendrites 
of the ganglion-cells are well stained. 
* Zeitschr. f. wiss. Mikr., xv. (1899) pp. 443-5. 
t Johns Hopkins Hosp. Bull., x. (1899). 
X Anat. Anzeig., xv. (1898) pp. 212-25 (10 figs.). 
