80 



Animal Micrology 



ing and sectioning in the same manner as for teeth. Do not 

 destroy the periosteum. Prepare likewise longitudinal sections 

 of a tarsal bone. 



Sectioning Bone by Grinding. 1. With a fine saw cut a thin 

 transverse section of the femur of a cat. Let it macerate in water 

 until quite clean, then dry it carefully. 



2. Grind the disk of bone between two hones, keeping the 

 hones parallel in order to avoid wedge-shaped sections. The sec- 

 tion is not thin enough until fine print can readily be distin- 

 guished through it. 



3. Wash the section thoroughly in water, transfer it to abso- 

 lute alcohol for 10 minutes, then to pure ether for half an hour 



4. After removal from the ether, clamp it between two slides 

 by means of a string or a rubber band and let it dry thoroughly. 



5. Place some xylol-balsam in the center of a slide and heat it 

 for a few minutes to drive off the xylol, then press the section of 

 bone down firmly into it and put on the cover-glass. The balsam 

 should not be thin enough to penetrate the tissue of the bone. 



MEMORANDA 



1. Proper Fixing Before Decalcification is necessary for the best results. 

 Muller's fluid (reagent 8, Appendix B) is perhaps the most common 

 reagent used in the fixation of bones or teeth. It requires 2 to 4 weeks 

 to fix properly. 



2. Failure to Stain Properly is due ordinarily to insufficient washing- 

 out of the acid. 



3. Teeth and Other Hard Objects may be prepared by grinding in the 

 same way as bone. 



4. For Other Decalcifying Fluids than nitric acid, see Appendix B, v. 



