18 PRACTICAL MICROSCOPY. 



is to be lessened, until the weight of the blade alone gives sufficient 

 friction. 



Kepeat the process fifteen or twenty times, and examine the blade. 

 If the nicks are yet visible, continue honing until they can no longer 

 be seen. Then draw the edge across the thumb nail. Do this lightly 

 and the sense of touch will reveal indentations which the eye 

 failed to recognize. Continue the use of the coarse stone until the 

 edge is perfect, as far as the thumb-nail test indicates. 



The knife is then to be carefully wiped, so as to remove any coarse 

 particles of corundum, and applied to the wetted Turkish hone with 

 precisely the same motions as were employed in the first process. Af- 

 ter a dozen or two strokes, examine the edge, by applying the palmar 

 aspect of the thumb, with repeated light touches, from heel to point. 

 This looks slightly dangerous to the novice, but it is an excellent 

 method of determining the condition. Of course actual trial with a 

 piece of hardened tissue is the best test. 



Some most skilful technologists prefer to finish by stropping. I 

 have not used a strop in my laboratory for over two years, preferring 

 to use the knife as it comes, highly finished, from the water-of-Ayr 

 hone. If a strop be employed, the leather should be glued smoothly 

 to a support of wood, otherwise the edge of the knife will become 

 rounded. 



Stropping is conducted in the same manner as honing, only the edge 

 of the knife follows the stroke instead of leading it. 



SUPPORTING TISSUES FOR CUTTING. 



Frequently small bits of tissue are required to be cut pieces too 

 small to be held with the fingers. I am in the habit of cementing 

 such tissues into a hole in a bit of ailantus or elder pith, when the 



FIG. 11. INSTRUMENT FOR SOLDERING TISSUE TO CORK SUPPORTS WITH PARAFFIN. 



It consists of an awl handle of wood into which a short piece of wire, preferably copper, is 

 driven and bent as shown. 



whole may be cut as one mass. Tissue is frequently cemented 

 to cork for convenience of holding in free-hand cutting; or the cork 



