56 Paraffin Method (chap. 5) 



6. Sections cling to block instead of knife, 

 a. Knife too dull or dirty. 



h. Increase tilt of knife. 



c. Paraffin too soft or room too warm. Try harder paraffin or cool 

 block. 



d. Infiltrating paraffin too hot, or too long exposure to solutions 

 which harden; soak in ^vater.-j- 



7. Tissue makes scratching noise while sectioning. 



a. Tissue too hard; paraffin too hot or too long exposure to solu- 

 tions which harden; soak in water.f 



b. Crystals in tissue; fixing reagents not removed sufficiently by 

 washing; calcium or silicon deposits present. (See pages 24 and 

 372.) 



8. Knife rings as it passes over tissue. 



a. Knife tilted too much or too little. 



b. Tissue too hard and springs back edge of knife; soak in water.f 



c. Knife blade too thin; try a heavier one. 



9. Sections curl, fly about or stick to things; this is due to electrification 

 from friction during cutting, especially in weather of low humidity. 



a. Increase humidity in room by boiling ^vater in open pan. 



b. Ground microtome to water pipe. 



c. Postpone sectioning luitil weather is more humid. Early morn- 

 ino sectionino^ often is best. 



d. See page 54. 



10. Sections are skipped or vary in thickness. 



a. Microtome in need of adjustment or new parts. 



b. Tighten all parts, including knife holder and object holder 

 clamp. 



c. Large or tough blocks of tissue may spring the knife: soak in 

 water.f 



d. Knife tilt too CTeat or too little. 



Mounting 



Slides and Cover Glasses 



Most microscopic materials (sections, whole moinits, smears, touch 

 preparations) are moimted on class slides and are covered with micro- 

 scopic cover glasses. A noncorrosive quality should be purchased to 

 insure a nonreacting surface. The slides may be obtained in the regular 

 3x1 inch size or in 3x2 inch for larger tissue sections. The brands 



