1 68 PRACTICAL PHOTO-MICROGRAPHY. 
than this, recourse must be had to the Thoma or the 
Schanze , or, better, to such an instrument as was 
designed by our friend Mr. G. L. Cheatle, of King’s 
College. 
The sections having been cut either in chains, or 
separately, are laid on clean glass slips, and filtered 
water is run in beneath them with a pipette, so that the 
sections float on the water. Heat is now applied to 
the lower side of the slip till the water is of such heat 
as almost to cause the paraffin to melt. The sections 
under this treatment will open up in a most satisfactory 
way, and this spreading may even be aided by a camel- 
hair brush. It is astonishing to what an extent we can 
open up an apparently fatally folded section in this 
way. The water is now run off the slip, and the slip 
with its section is allowed to dry naturally or in the 
cool incubator, about ioo° Fahr. 
When the sections are quite dry, the paraffin is 
removed by two baths for a minute each in mineral 
naphtha, and the latter is removed by a bath of spirits. 
(The dry slips and sections may be kept for any length 
of time before the paraffin is removed.) 
1 he foregoing processes are in the main due to Dr. 
Brook and Mr. Gulland, of Edinburgh. Sections 
treated as above will hardly leave the slips under any 
provocation; but sometimes tissues which have been 
thoroughly tanned with “Muller” or a chrome salt will 
leave the slips. In such cases we must use a fixative 
solution such as two per cent, albumen, or Mayer’s— 
albumen and glycerine. But the former process is far 
superior when it is effective. 
