1877.] The Sledge Microtome. | 209 
. barely moistened with spirits of turpentine, and then put on a 
slide and covered with a drop of turpentine, which dissolves in 
a few seconds all the paraffine. The sections can then be un- 
rolled with the brush. If the object is colored in toto, the sec- 
tions are all ready for mounting, which may be done by wiping 
off the superfluous turpentine with a bit of cambric. The addi- 
tion of a drop of balsam (or better still of a mixture of one part 
Canada balsam and two parts white Dammar varnish) and put- 
ting on a cover slip complete the preparation. 
If, however, the object has not been colored beforehand, the 
sections must be stained singly; to do this, when they have 
been imbedded in paraffine they must be left half an hour in a 
few cubic centimeters of spirits of turpentine, then one fourth of 
an hour in absolute alcohol, after which the alcohol should be re- 
newed and the sections left for another quarter of an hour, where- 
upon they can be at once stained and mounted either in balsam 
or glycerine in the usual manner described in all hand-books of 
microscopy or histology. 
This method of imbedding in paraffine has the great advan- 
tage that objects once prepared in this way may be kept indefi- 
nitely and be cut at any time, or even be partially cut, and then 
be stowed away to be cut again by and by, it being only neces- 
sary to cover up the exposed surface of the object by dropping a 
little melted paraffine upon it. I have a small collection of such 
objects, each one bearing a number referring to a catalogue, so that 
there are several things of which I can make a first-rate prepara- 
tion in ten minutes at any time. 
I have found it convenient in making long series of sections to 
designate each series by a letter of the alphabet, and after having 
been once through to begin anew AA, AB, AC, and then again 
BA, BB, BO, and so on, I am accustomed to put several sections 
on each slide, which are numbered. My catalogue shows what 
each series is, and also anything about any section I choose to 
note, thus: “& W., Planaria tora, transverse sections, 2 (slide num- 
ber) through the brain, III. (number of section) through the eyes. 
In this way any particular section out of many thousands can be 
quickly found. 
The sledge microtome can be obtained of Thomas A. Upham, 
mechanician, 17 Harvard Place, Boston, Mass., for $25. The 
knives have, at present, to be imported from Windler, Dorotheen- 
Strasse 3, Berlin C, where they cost 6 marks (2 thalers) apiece. 
ut Mr. Upham hopes soon to be able to supply knives himself. 
VOL, XI. — No, 4, 14 
