MICROSCOPICAL TECHNIQUE, ETC. 167 
this case the tissues remain in the dish till impregnation 
is complete ; the dish is then floated on cold water till 
a thin skin of cooled paraffin forms on the top, when 
the dish is pushed under the water, and the whole mass 
of paraffin cooled as rapidly as possible. The dish is 
then placed in hot water, and the mass removed and 
trimmed for the microtome. The metal L pieces may 
also be used. 
The simplest microtome made is that known as the 
Cathcart , and when this is used with a plane-iron set in 
a wooden handle, wonderfully good sections can be cut 
with it. It is, however, hardly the scientific and 
accurate instrument required for the best work, and an 
instrument of higher class will be found in the Cam¬ 
bridge rocking microtome. Very fine sections are cut 
with this, provided we do not attempt too large pieces 
of tissue. The instrument which we consider the best 
is the Minot (fig. 29), which may be obtained from Mr. R. 
Kanthack, London, and others, and this we say after con¬ 
siderable experience of several of the best-known micro¬ 
tomes. This instrument holds the tissue firmly, and 
cuts it in straight lines, and the devices for “orientation,” 
and for regulating the thickness of the sections, are 
admirable. In the simpler form the thinnest section 
that can be cut is the 300th of a millimetre, and this 
comes well within our definition of a thin section ; but 
another form is made, which will cut sections con¬ 
siderably thinner. Another point is that with this 
microtome we can section tissues with a surface of an 
inch and a half square at least. For surfaces larger 
