ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
495 
in every way as satisfactory as xylol. Owing to its cheapness it is 
possible to use benzin in much larger quantities than xylol, and the 
requisite degree of freshness is easily obtained. 
Many slides were prepared without the preliminary coating with 
albumen, and in all cases the collodion coat was sufficient to keep the 
sections fastened to the slide, but owing to the well-known uncertainty 
in making a film of collodion adhere to glass, the albumen was used as a 
safeguard against failure, the alcohol in the collodion serving to coagu- 
late the albumen. Different per cent, solutions of collodion were tried, 
and mixtures varying in the proportions of ether and alcohol. No 
difference was found in the results given by the various mixtures, but 
the 3/4 per cent, solution was the most satisfactory. 
The chief advantage of this method is that it dispenses with the need 
for an alcohol lamp ; an important, and, in the hands of the inex- 
perienced, a somewhat dangerous adjunct of the laboratory is thus 
removed from constant use. The greatest disadvantage is that, as in all 
collodion methods, the collodion is liable to take the stain and refuse to 
give up the colour to treatment. Practically, however, in using the 
ordinary hsematoxylins, eosin, picric alcohol, &c., there is no difficulty ; 
it is only with the stronger stains that trouble is found. The use of this 
thin coat of collodion is a simple and effective method for general histo- 
logical purposes.” 
Preparing Liquidambar for Mounting.* — Prof. H. G. Piffard pro- 
pares liquidambar for mounting in the following manner. A pound of 
the crude gum (an exudation from Liquidambar styraciflua L.) is liquefied 
in a water-bath, and then filtered through a Plantamour’s funnel lined 
with two or three thicknesses of cheese cloth. When cold, one pound of 
xylol is added. The bottle containing the mixture should be shaken 
several times daily for at least two weeks. It is then filtered two or 
three times through absorbent cotton or Swedish paper. The thin trans- 
parent filtrate is next inspissated at a gentle heat until it has the con- 
sistence of molasses. Two parts of this should be mixed with three 
parts of monobromid of naphthalin and heated gently. The result is a 
clear amber-coloured fluid, the refractive index of which should be 
brought to 1 * 625 by the addition of either of the ingredients as may 
be required. Preparations mounted in this medium are quite permanent. 
Zenker’s Fluid as a Fixative.| — Dr. A. Mercier records his expe- 
rience of this fluid, the formula for which is as follows : — Sublimate, 5*0; 
bichromate of potash, 2*5; sulphate of soda, 1 ; acetic acid, 5*0; dis- 
tilled water, 100*0. The acetic acid should be added to the rest of the 
fluid just before using, 10 ccm. to 200 ccm. of the mixture, and a large 
quantity is to be used, about fifty times the bulk of the piece or organ. 
The objects used were fowls’ embryos from the second to the seventh day, 
organs of some mammals (cats, bats, rabbits), and worms, young frogs, 
and salamanders. The smaller objects were immersed for 24 hours, 
the larger for 48 hours. They were then washed for 6 hours in running 
water ; then 6 hours in 50 per cent, spirit, changed thrice ; then 6 hours 
in 70 per cent, spirit, once changed; then 2—3 days in 90 per cent. 
* Med. Record N.Y., May 4, 1895, p. 547. 
t Zeitschr. f. wiss. Mikr., xi. (1895) pp. 471-8. 
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