154 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



hardened substances (tiorta, eyes, cftrtilage, substances imbedded in 

 paraffin, &c.) instead of being even are thicker at one point than at 

 another, or the sections appear striped, their thickness varying in 

 steps. He has found that the cause lies in the fact that hard sub- 

 stances bend the edge of the ordinary knife and that this can bo 

 prevented by using knives with stronger edges and shorter blade like 

 E Z in figs. 32— i, which at the same time are cheaper. For convenience 

 in sharpening the knife a movable handle F is attached to the blade 

 by the screw r. 



The knives should moreover be attached to the microtome in a 

 different way to that ordinarily adopted. The new holder is also shown 

 in figs. 32-4. This has two forks O and O' by which it can be fastened 



to the carrier Y C of the microtome and clamped by S, the knife being 

 clamped by v acting on the piece G. Fig. 33 shows the position 



