12 PREPARATION AND MOUNTING 
The writer has little or no experience of this plan, he 
therefore quotes from Frey as follows :— 
“The preparation is allowed to freeze (by contact, it is 
presumed, with a freezing mixture or solution) until it as- 
sumes a consistency which will permit fine sections to be 
made with a cooled razor. The object is more convenient to 
handle if it is allowed to freeze on a piece of cork. Nerves 
and muscles have been treated in this manner with good 
results. Glands (salivary), livers, spleens, the lungs, skin, 
and the bodies of embryos (see Beale’s process for the same. 
in this work), also ganglia, afford excellent appearances. 
Indifferent (or neutral) media, such as iodine serum, are to 
be used in examining such sections. Or the preparation may 
be held in paraffine wax (diluted or not with oil), or tallow, 
which have been melted, and the object suspended or 
plunged in them until they cool, and the cooling may be 
carried further, if needed, by freezing.” 
In reference to this subject, Mr. Kesteven informs the 
author that he has found the parafiine composition more 
useful for brain than spinal cord. The former can be cut 
into any angular shape, and be so held steady for slicing; 
but the cord, being round, becomes loosened in its setting of 
wax (or paraffine), and revolves with the pressure of the knife. 
¥For either brain or cord he prefers hand-cutting with a very 
sharp razor, after the manner of Lockhart Clarke (see Mr. 
Kesteven’s paper in St. Bartholomew’s Hospital Reports). 
If many sections are to be made from a brain, machine- 
cutting saves much time. The razor should have some 
spirit of wine dropped on it, so as to prevent the sections 
adhering. The cutting machines are generally graduated 
(by a screw and index) on the upward movement, so as to 
enable one to judge of the thickness of the section; but as 
the brain substance and paraffine are both yielding to a cer- 
tain extent, the reading must be taken with allowance. 
