26 THE MICROSCOPE. 
have named the attachment a Section Flattener (see Fig. 1, b). It 
was first attached to a razor and then to a section knife; in both 
cases it has been found entirely satisfactory, as it prevents the roll- 
ing of section even when the object is imbedded in the hardest 
paraffine. Indeed, in using it the imbedding mass may be safely 
about three degrees C. higher melting point than is permissible 
without it. A section knife or razor with this attachment may be 
used with any microtome or free hand. Besides its special use in - 
preventing the curling of sections, the section flattener serves as a 
guard to the edge of the knife. 
A B e D 
The section flattener consists of a rod (b) of spring brass about 
5 mm. in diameter, flattened on two sides (B and D), extending 
parallel with the edge of the knife and projecting about 2 mm. 
beyond it. Opposite the cutting edge, the space between the rod 
and knife is about 1 mm., while nearer the back of the knife the 
distance is greater (Fig. 1 D, a,b). At each end the-rod is bent at 
right angles. Next the handle it passes through a hollow cylinder 
(Fig. 1, d), into which it is secured by a milled nut (Fig. 1,c). At 
the free end of the knife, the rod is hooked over the back of the 
blade (Fig. 1, A), the spring of the wire securing it firmly. At the 
two angles of the rod, it rests on the blade so that in cutting sec- 
tions any amount of pressure may be applied at these points. The 
rod is attached to the knife by means of a clamp, which consists of 
two pieces clasping the tang and held together by a screw (Fig. 1 
C). To clean the knife and rod, or to remove sections, the rod may 
be raised as it swings freely in the hollow cylinder attached to (d). 
The rod may be entirely removed—as is necessary in sharpening the 
knife—by removing the milled nut (c); the entire apparatus may be 
removed from the knife by loosening the screw (f). 
