THE PARAFFIN METHOD 
117 
more than 15 years. Many fail at the first attempt and go back to 
the continual drudgery of sharpening microtome knives. If the 
holder is placed in the microtome at the angle used for a microtome 
knife, failure is certain, because the blade will scrape rather than cut. 
The angle should be considerably nearer vertical than in the case of a 
microtome knife. A study of Figure 6 should enable anyone to secure 
the proper angle. 
b) Keep the microtome well oiled and clean. 
c) Trim the block so that each section shall be a perfect rectangle. 
Fig. 24.—The ribbon 
CC 
A ribbon of sections like that shown in Figure 24 A is much better 
than one like B of the same figure, because sections will usually come 
off in neater ribbons if the knife strikes the longer edge of the rectangle, 
so that the sections are united by the longer sides rather than by the 
shorter. Crooked ribbons are caused by wedge-shaped sections, and 
are always to be avoided, because they 
make it difficult to economize space, 
and also because they present such 
a disorderly appearance. The knife, 
which should be placed at a right 
angle to the block and not obliquely, 
should strike the whole edge of the 
block at once, and should leave in the 
same manner. 
If sections stick to the knife, it 
may be that the knife is too nearly 
parallel with the surface of the block, as in Figure 25 A. By inclining 
the knife as in Figure 25 B, this difficulty is often obviated. A split or 
scratch in the paraffin ribbon may be caused by a nick in the knife. 
Use some more favorable position of the edge, or sharpen the whole 
A B 
Fig. 25.—Position of knife 
