162 THE MICROSCOPICAL NEWS. 
to the acme of scientific perfection. The blood may be followed 
through every part of the body, with the kidneys, the heart, and 
the gills all in view, and their connecting veins and arteries 
beautifully exhibited. 
(Zo be continued. ) 
COLLODION AS A FIXATIVE FOR 
MICROSCOPICAL SECTIONS. 
ECTIONS fixed by means of a solution of collodion in clove 
oil, as recommended by Schiallibaum, may be coloured on the 
slide. The method is as follows: The solution, which is prepared 
by dissolving one part collodion in three or four parts clove oil, is 
applied to the slide by means of a fine brush at the time of using. 
The sections having been arranged, the slide is warmed for a few 
minutes (5—1r10) in the oven of a water-bath in order to evaporate 
the clove oil. The sections may next be freed from the imbedding 
mass and coloured according to desire. If the film of collodion 
be too thick, cloudiness is likely to arise between the sections. 
The cloudiness can be removed by the use of a brush, wet with 
clove oil, after the sections have been anhydrated by absolute 
alcohol. 
Gage, who had begun to experiment with collodion before 
Schallibaum’s method was published, recommends that the col- 
lodion and clove oil be applied separately: ‘A solution of 
collodion is prepared by adding to 2 grams of gun-cotton (that 
used by photographers is good) 54cc. of sulphuric ether and r&cc. 
of 95 p.c. alcohol. After the gun-cotton is entirely dissolved the 
solution should be filtered through filter paper or absorbent cotton. 
The slides are coated by pouring the collodion on one end allow- 
ing it to flow quickly over the slide and off the other end into the 
bottle. The prepared slides should be kept free from dust. As 
the collodion will not deteriorate after drying on the slide, any 
number of slides may be prepared at the same time. Before using 
a ‘slide it should be dusted with a camel’s-hair brush, and with 
another brush the collodionised surface of the slide should be 
thinly painted with clove oil * * * * ‘The sections are 
arranged as in the shellac method. ‘The slide is warmed over an 
alcohol lamp and then heated in a warm chamber so as to drive off 
the clove oil. After cooling it may be placed in a wide-mouthed 
vial of turpentine, chloroform, xylol, or refined naphtha, to remove 
the paraffin. Naphtha is very cheap, and is the best agent we 
