CHAPTER IV. 



PREPARATION AND STAINING OF TISSUE 

 SECTIONS. 



(A) METHODS OF HARDENING AND DECALCIFYING 

 PREPARATIONS. 



To harden small organs, such as the viscera of a 

 mouse, they must be placed on a piece of filter 

 paper at the bottom of a small, wide-mouthed glass 

 jar, and covered with about twenty times their 

 volume of absolute alcohol. Larger organs, patho- 

 logical growths, etc., are treated in the same way, 

 but must first be cut into small pieces, or cubes, 

 varying from a quarter of an inch to an inch in 

 size. Muller's fluid may also be employed, and 

 methylated spirit may be substituted for alcohol, 

 from motives of economy. Tissues hardened in 

 absolute alcohol are ready for cutting in two or 

 three days, and those hardened in Muller's fluid in 

 as many weeks. 



Teeth, or osseous structures, must first be placed 

 in a decalcifying solution, such as Kleinenberg's. 

 When sufficiently softened they are allowed to soak 



