HOW TO USE THE MICROSCOPE S31 
oven (Fig. 31) should not be much higher than the melting- 
point of the paraffin. 
The specimen is now ready to be embedded. First make a 
mould of cardboard or a lead-embedding frame (Fig. 32), melt 
the paraffin, and then place the 
specimen in a manner that will 
facilitate cutting. Remove the 
excess of paraffin and cut when 
desired. 
In using the collodion method 
for embedding fibrous speci- Fic. 32.—Paraffin Blocks 
mens, as wood, bark, roots, etc., 
the specimen is first fixed with picric acid, washed with water, 
cleared in ether-alcohol, embedded successively in two, five, 
and twelve per cent ether-alcohol collodion solution, and finally 
embedded in a pure collodion bath. 
CUTTING SECTIONS 
Specimens prepared as described above may be cut with a 
hand microtome or a machine microtome. 
HAND MICROTOME 
In cutting sections by a hand microtome, it is necessary to 
place the specimen, embedded in paraffin or held between 
pieces of elder pith, carrot, or potato, over the second joints 
of the fingers, then press the first joints firmly upon the speci- 
men with the thumb pressed against it. If they are correctly 
Fic. 33.—Hand Microtome 
held, the specimens will be just above the level of the finger and 
the end of the thumb, and the joint will be below the level of 
the finger. 
Hold the section cutter (Fig. 33) firmly in the hand with 
