THE MICROTOMIST'S VADE-MECUM

of by French writers as mdthodes d'inclusion, or mthodes        Il1'
d'enrobage).                                                   SIio
217..Before setting out the formuie for the different im-      boot Ot
bedding masses that have been recommended, it is necessary
to say a few words as to the details of manipulation in the irst
process of imbedding.                                           1i o t
To imbed an object in such a substance as liver or spinal      prafV
cord (which does not strictly come under the category of an      thej
imbedding mass at all, as defined above) nothing more is neces-  ingOsili
sary than to take a piece of fresh liver or cord of convenient   1115di
dimensions, scoop-out in it a hole of the size of the object to dedr
be imbedded, place the object in the hole, and immerse the hl6t
mass in alcohol until such time as the mass is sufficiently      fruit
shrunken and hardened to hold the object firmly and permit       for
of section cutting.                                              of PP
If pith be employed, a cylinder of pith is halved longitu-     git
dinally, a cavity corresponding to the object to be imbedded     good
is made by scooping out the inner face of either half-cylinder, Ih
the object placed in position between these, and the cylinder    tenr
pushed into the well of a microtome (which it should fit accu-    t tri
rately), and moistened with alcohol (or other suitable liquid)   hre
in order that the pith may swell round the object. It should       (
be noted that it is better to make the cavity in the pith by simple  as
pressure and kneading (e.g. with the handle of a scalpel) than   loris
by excavation of material; the pith-cells that have been flat-
tened and pushed to one side by the kneading, tend to regain     chiih
their normal form and position during the soaking in alcohol,     Rj
and their resilience causes the imbedded object to be grasped    h
with an often surprising tightness. If the cylinder of pith     tbo
does not fit the holder of the microtome accurately in the dry   1ek
state (which it should do if possible) it should be wedged in    Br
by means of strips or thin wedges of kneaded pith inserted        01t
dry, and the whole afterwards soaked. With well-hardened        lii
objects this method, if skilfully carried out, allows of very ac-  thor
curate section cutting.

164