FARRANT’S MEDIUM FOR MOUNTING MOSSES. 
William B. Davis. 
Dr. R. H. Ward once wrote that for some objects of microscopical inter- 
est Farrant’s Medium nearly accomplishes the paradox of enabling one to 
mount specimens without the trouble of mounting them. It is certain, how- 
ever, that if more workers with the microscope know just how satisfactory 
this gum and glycerine medium was, that it would be in more demand. 
A great many of us are too busy to make- permanent glycerine 
or balsam mounts. Frequently when working on the -mosses they are exam- 
ined in glycerine ; and if of sufficient interest, are laid aside without being 
sealed, but in this condition they quickly spoil. No further labor than 
mounting in water or glycerine is entailed by using the Farrant’s Medium. 
The advantages are many. In a few hours the gum hardens at the edges 
and the slide can be cleaned without risk of disturbing the specimen. In 
fact such slides can be put away for years just as mounted, and then extra 
fluid can be scraped away with a knife, when desired. 
The following suggestions for those not accustomed to this rapid way of 
working may be of use : 
(a) Do not use too much of the medium. With a little experience, an 
amount sufficient to flood the object nicely to edge of the cover glass will be 
used. This will do away with the necessity of clearing away the excess ; 
although such excess can be cut away with a knife or washed in a few hours. 
(b) Remove air bubbles with a needle and breathe upon the slide and 
cover glass before making contact. This moistening of the surface will often 
prevent the entanglement of air bubbles. 
(c) The object may be mounted directly or from water, glycerine, or even 
a weak alcoholic solution. 
(d) If the object is thick it might be well to keep in view for a few days 
and applying when required a drop of the medium to any air bubbles which 
may show themselves at the edges. 
By adopting this method of permanently mounting moss specimens, in 
a few years, one may be the possessor of a fairly representative set of micro- 
scopic mounts. 
The medium can generally be secured from any of the dealers in micro- 
scopical materials for about 25 cents a bottle, but for those who desire to put 
up their own, the following recipe of Prof. A. B. Aubert is given: 
Gum arabic 1 ounce 
Glycerine 1 ounce 
Water 1 ounce 
Arsenious oxide 1 ^ grains 
Dissolve the oxide in water, then the gum, without heat; when entirely 
dissolved add the glycerine, take care not to form bubbles ; can be filtered 
through fine flannel. Philadelphia, Pa. 
