Sectioning 



53 



of the knife with anything hard. Fragments of paraffin can be flicked 

 off with a camel hair brush, or removed with a finger tip. Scratches 

 appearing in sections often can be remedied by rubbing the knife edge 

 with a finger tip, up- 

 ivards. Also try this 

 motion on the back of 

 the knife; it will re- 

 move bits of para- 

 ffin which can cause 

 scratches. Cleansing 

 tissue dipped in xy- 

 lene also is helpful. 

 (Warning: discard the 

 first section after 

 cleaning the knife; it 

 probably is a thick 

 one.) When all sec- 

 tioning is completed, 

 xylene must be used 

 to clean the knife; 

 leave no corrosive ma- 

 terial on its edoe. 



Section with an easy rhythm; never rush, or variable thickness of 

 sections is likely to occur. As the sections move down on the knife they 

 form a "ribbon," each section adhering to the one that precedes it as 

 well as the one that follows it. During the cutting of the sections, a bit 

 of heat is generated, enough to soften the paraffin and cause the indi- 



Figure 12. Tissue blocks mounted on an object 

 disc or luooden block and ready for sectioning. 



Figure 13. Insufficient 

 paraffin knife tilt. 



Figure 14. Excessive paraffin knife 

 tilt. 



