KILLING ANIMALS FOR DISSECTION. 79 



edge. (Fig. 28.) (3) The blade should be turned at the end of 

 every sweep across the strop, thus drawing it from right to left as 

 often as it is drawn from left to right. 



B. (1) Use first the red and then the black side of the strop. 

 (2) Press only moderately. The nearer a perfect edge is attained 

 the more lightly should one press. 



(3) Continue the stropping on the red side until the knife will 

 cut a hair of the head 1 cm. from the point where it is grasped by 

 the fingers ; then employ the black side. 



(4) Continue to use this side until the knife will cut a hair from 

 the head 2-3 cm. from the point where it is held, or, what is a better 

 test, until it will cut the fine hairs on the dorsum of the hand and 

 wrist half a centimeter from their base when the knife is moved 

 distad toward the ends of the fingers. If the knife has a perfect 

 edge it will cut these fine hairs so easily that one can hardly tell by 

 the feeling when a hair is divided. 



186. Scissors. These are much more difficult to sharpen than 

 scalpels, and the fine ones should be sent to the makers unless 

 one is very skillful. Place the blade so that the oblique face 

 formed by grinding shall rest flat on the stone. Draw the blade, 

 edge foremost, across the stone with a curving sweep as for scalpels 

 ( 184, C [3] ). Test for sharpness with the finger or by attempting 

 to cut moistened tissue paper ( 184, F [3] ). 



187. Tracer, Syringotome and Concave Edges Generally. 

 In sharpening instruments of this kind one should use the edge of 

 the stone instead of its face. The edge of the stone should be some- 

 what rounded. In sharpening, draw the blade along the stone so 

 that the edge precedes the back as for scalpels ( 184, C [3] ). Test 

 the sharpness with the finger ( 184, F [3] ). 



188. The care and sharpening of instruments are considered by Mojsisovics, A, 13 ; 

 Holtzapffel, A, III, 1026-1156 ; Hyrtl, A, 23-27 ; Straus-Durckheim, B, 1, 158-160. 



KILLING ANIMALS FOR, DISSECTION. 



189. There is usually no difficulty in taking a cat when it is 

 wanted. Such as will not come when called may be secured by 

 means of a strong net, or by using a bag attached like a net to a 

 hoop and pole. 



The bag referred to is of strong coarse material, and commonly 

 used for oats. In such a bag the cat may be left for several hours ; 



