1885. | ; Microscopy. 627 
the advantages of the shellac method of Giesbrecht, and offers, at 
the same time, the best means of meeting the difficulties of stain- 
ing objects in toto, The only other fixative thus far known which 
claims to accomplish similar results is that introduced by Mayer 
(“ Microscopy,” Feb., 1884). 
Prof. Gage,’ who began to experiment with collodion as a fixa- 
tive prior to the publication of Schallibaum’s method, has given 
some valuable directions respecting its preparation and applica- 
tion. (3age- applies the collodion and clove oil separately, first 
coating a number of slides with collodion, which is poured on to 
one end of the slide and allowed to flow quickly over it and off 
into the bottle; and then, at the time of using, adding a wash of 
clove oil. In order to remove any cloudiness that may arise in 
the collodion film, a little clove oil is added to the balsam. 
_ The use of collodion to prevent the crumbling of brittle sec- 
tions originated with Norman N. Mason.? The same method was 
employed in Semper’s laboratory by Timm,’ Will“ Sarasin, Sharp 
and others ; and Mark has found it indispensable in sectioning the 
ova of Lepidosteus. Mason applied the collodion by means of a 
fine brush, taking up a small drop and placing it “in the center of 
the object so as to allow it to flow out on all sides to prevent the 
formation of air bubbles. After being allowed to harden a min- 
ute, the section may be cut and placed on the slide with the film 
of collodion underneath,” 
Mark and others who have used collodion for the same pur- 
pose, simply paint the cut surface of the object with a thin film a 
few seconds before making each section. 
Celloidin Injections—In the formation of injection masses 
collodion plays still another important role, for the discovery of 
which we are indebted to Schiefferdecker.6 It can be made to 
but not enough to form a serious drawback. It is prepared in 
different ways according to the color to be given to the injection. 
A. Asphalt Celloidin Injection —1. Pulverized asphalt placed in 
a well closed bottle of ether and allowed to remain twenty-four 
hours, during which the mixture must be several times shaken. 
: brown-colored ether is turned off, and small pieces of 
celloidin dissolved in it until the solution flows like a thick oil.’ 
1 The Medical Student, p. 14, Seane, 1883. 
25. 
8Semper’s Arbeiten, VI, p. 110, 1883. 
5 Semper’s Arbeiten, VI, 1883. 
“L & p 20i. : 
1The pulverized alt can be used many times over for coloring the ether, as 
very little of it will dissolve in twenty-four hours. | 
