en. 



PARAFFIN METHOD 



295 



S 443. Trimming the End of the Block for Sectioning. 

 Sharpen the end to be cut in a pyramidal form, being sure to leave 

 2 millimeters or more of paraffin over the tissue at the end as well 

 as on the sides. The block is trimmed in a pyramidal form so that 

 it will be rigid. Take particular pains that the opposite faces at the 

 end of the block are parallel, and all the corners right angles. 



S 444. Making Paraffin Sections. Put the paraffin block 

 or the metal holder in the clamp of the microtome. Arrange the 

 block so that one side of the pyramidal end is parallel with the edge 

 of the knife, then tighten the clamp, and if an automatic microtome 

 is used make sure that the section knife is also tightly clamped by 

 the proper set screws. It is well to have the knife lean slightly 

 toward the paraffin block (Fig. 239). 



FIG. 233. The Minot automatic rotary, microtome for paraffin sectioning 

 (Sections from i /.i to 25 ft may be cut on this instrument. ) (Cut loaned by 

 the Bausch & Lomb Optical Co.). 



