The bones from one of the legs should be carefully cleaned of its muscles, cut into several pieces, and placed in a solution of fifteen and one-half grains chromic acid, one-half drachm nitric acid, and six ounces water.  Change the fluid frequently until the bones are sufficiently softened, and then change to alcohol.

Section cutting machines for cutting sections can be procured of the dealers, but a very simple and effective one can be easily made if one does not wish to go to the expense of buying an instrument.

A strip of wood twelve or fourteen inches long and about two inches wide has attached to its center a bridge-shaped piece of wood, a, Fig. 1.  This is covered with a brass plate, c, pierced with a hole one-half of an inch in diameter.  This hole extends through the wood, and is fitted with a piston.  Two long narrow inclined planes of nearly equal inclination, b, b, grooved to slide on each other, are placed under the bridge; the lower is to be fastened to the board; the end of the piston rests on the upper one.  The object from which we desire to cut a section is placed in the hole, in the piston.  If the upper plane be pushed in, the piston will be forced upward, and with it the object.  As the inclination of the plane is very gradual, the vertical motion will be very slight as compared with the horizontal.

When the object is raised a little above the brass plate, a keen edged razor, thoroughly wet, is pushed over the hole, cutting the object.  This gives the section a smooth surface, and even with the plate; now push the plane forward one-eighth to one-quarter of an inch, and cut again; this will give a thin section of the object.  The thickness of the section depends, of course, on the distance the wedge is pushed.

With a little practice, much better sections can be cut by the hand than by any machine; this does not apply of course to large sections.  A razor of good steel, with a blade thin and hard, are the most essential points in an instrument for hand cutting.  For ordinary purposes it is not necessary to have the blade ground flat on one side, although many prefer it.  The knife should always be thoroughly wet, in order that the cut tissue may float over its surface.  Water, alcohol or salt and water may be used for this purpose.

[Illustration:  FIG. 1.]

To out a section by hand, hold the object between the thumb and first two fingers of the left hand, supporting the back of the knife by the forefinger.  The knife is to be held firmly in the right hand, and in cutting should never be pushed, but drawn from heel to point obliquely through the tissue.  The section should be removed from the knife by a camel’s hair brush.

When the object is too small to hold, it is usually embedded in some convenient substance.  A carrot is sometimes very useful for this purpose.  A hole rather smaller than the object is cut out of the middle.  Put whatever is to be cut into this, and cut a thin section of the whole.  The carrot does not cling to either the knife or the section, and the knife is wetted at every slice by it.