412 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
the water-bath will soon insure a complete mixing. Into this bottle 
drop a small lump of camphor. 
This medium needs a little warming (about 110° Fahr.) to make it 
fluid for use. 
Preserving Animals.^ — Dr. C. J. Cori, after trying various fixatives 
as reagents for rapidly narcotizing small invertebrate animals, such as 
hot sublimate, chloral hydrate, ethyl-alcohol, certain alkaloids, such as 
strychnia and cocain, found that ordinary wood-spirit or methyl-alcohol, 
since it has little action on albumen and possesses sufficiently satisfactory 
narcotic properties, gave the best results. The formula for the solution 
is: — Methyl-alcohol 96 per cent, 10 ccm. ; water, 90 ccm. ; sodium 
chloride, 0*6 grm. The addition of the salt prevents the too great 
maceration of the tissues. 
For preserving and hardening the author found that chrom-osmium- 
acetic acid in the following proportions gave excellent results : — chromic 
acid 1 per cent., 25 vols. ; acetic acid 2 per cent., 5 vols. ; osmic acid 
1 per cent., 1 vol. ; water, 69 vols. The specimens are said not to 
become blackened, and stain quite well. 
If objects contain lime salts, these neutralize the acids, an incon- 
venience which can be obviated by using large quantities of the solution 
and frequent renewals of the fluid. In the fluid the animals remain, 
according to size, from 2-48 hours ; they are then washed in running 
water for 6-72 hours, then placed in 50 per cent, spirit, and finally in 
70 per cent. 
The osmic acid is dissolved in distilled water to which so much per- 
manganate of potash has been added as gives it a faint rose colour. A 
little of the salt should be added to the solution from time to time, or 
when the colour is beginning to fade. 
The osmic solution is best kept in yellow or black glass bottles with 
two grooves in the stopper, a device which allows large drops to be 
obtained without removal of the stopper. 
Agar as a Fixative for Microscopical Sections.f — M. A. Gravis 
recommends agar as a medium for fixing sections to the slide. Accord- 
ing to the author it possesses several conspicuous advantages. It is 
quite liquid at the ordinary temperature ; the sections can be arranged 
on the slide with great ease. Air-bubbles never appear beneath the 
section. Vegetable cells, which often become distorted when imbedded in 
paraffin, resume their shape and original dimensions. When well dried 
this fixative is insoluble in all reagents, except in distilled water. The 
specimens may be mounted in either balsam or glycerin. 
The fixative is prepared by soaking half a gram of agar in distilled 
water for some hours. It is then heated gently until it boils. It is 
then boiled for about 15 minutes so that the agar may be completely 
dissolved. When cold it is filtered through a fine cloth and preserved 
in stoppered bottles. 
In order to make the fixative stick properly, the slides must be 
perfectly clean. Ifr is best to boil the slides in water acidulated with 
hydrochloric acid, and then, having rinsed them in distilled water, dry 
them on a clean cloth. The fixative is put on the slide with a brush. 
* Zeitschr. f. Wise. Mikr., vi. (1889) pp. 437-42. 
t Journ. de Microgr., xiv. (1890) pp. 83-5. 
