ON SECTION CUTTING. 11 
be placed for a few hours in 30 per cent. alcohol, and then 
transferred to 50 per cent. alcohol: on the following day they 
should be transferred to 70 per cent. alcohol, which should be 
changed daily until the specimens are colourless: they may 
then be left in 90 per cent. alcohol until required. 
C. Staining. 
The hardened specimens, if not too large, may now be stained 
with either hematoxylin, borax-carmine, or picro-carmine ; they 
should then be placed back in 90 per cent. alcohol and trans- 
ferred from that to absolute alcohol immediately before im- 
bedding. If too large to stain whole, the sections must be 
stained after cutting. 
D. Imbedding. 
. The preparation of sections is greatly facilitated by imbedding 
the specimen in some waxy substance. For this purpose various 
materials have been employed, but by far the most useful is 
paraffin, which is used in the following manner :— 
The stained specimen is placed in absolute alcohol for an 
hour or two in order to completely dehydrate it. It is then 
transferred to turpentine, in which it is left for half an hour or 
more until completely saturated. From the turpentine it is 
transferred to paraffin, which is kept by means of a water bath 
at a temperature just above its melting point. In. this it is 
left for several hours, or even for a whole day, in order that it 
may be thoroughly permeated. It is then placed in a small 
box of paper, or other material, filled with melted paraffin. 
By means of hot needles it can readily be arranged in any 
desired position; and then the paraffin should be allowed to 
cool. 
E. Section-Cutting. 
When thoroughly set the block is removed from the box, and 
the paraffin pared away with a knife until the specimen just 
comes into view. 
The block is then placed in a microtome, and cut into thin 
sections. These may be transferred one by one to a slide, but 
a great saving of time is effected by the method of cutting 
continuous ribbons devised by Mr. Caldwell. 
This depends on the fact that if the paraffin is of proper 
consistency the successive sections, as they are cut, will stick 
