10 METHODS IN PLANT HISTOLOGY 
holder should not be inclined toward the paraffin as far as the micro¬ 
tome knife is inclined. The exact angle cannot be given, since it will 
vary with the amount the blade is allowed to project beyond the holder. 
But, just as in case of the microtome knife, which, when sharpened 
with a back as it always should be, has a double 
bevel like that of the safety-razor blades, the angle 
should be as near the vertical as possible. With 
either a microtome knife or blade in a holder, the 
paraffin block will hit the shoulder of the bevel after 
the section is cut if the position be too nearly 
vertical. A study of Figure 6 should enable anyone 
to get the proper orientation. 
When the Gillette blade begins to lose a little of 
its effectiveness for microtome work it will make 
two or three scalpels. With a pair of stout shears, 
cut the blade into pieces, as indicated in Figure 7. Take a small 
steel nail and flatten the head and upper part by laying it upon a 
piece of iron and hitting it with a hammer, or by squeezing it in a vise; 
Fig. 6. —Proper 
relative positions of 
holder, Gillette blade, 
and paraffin. 
3 
Fig. 7. —Scalpels made from Gillette blades, showing a blade which has been cut into pieces 
with shears, three of the pieces soldered to nails with flattened heads, and one of the pieces used in 
an ordinary needle-holder. 
then solder the blade to the nail, and use the scalpel in an ordinary 
needle-holder, or drive the nail into any wooden holder. A dozen of 
these scalpels can be made in ten minutes. 
