18 EMBEDDING MEDIA. 



passed into 90 p. c. Alcohol, and then into Absolute Alcohol, 

 in which it must remain for not less than 3 hours. It is next 

 placed in ten times its bulk of Chloroform or Benzol until 

 thoroughly saturated; then small pieces of the Paraffin 

 are added to the Chloroform or Benzol until no more will 

 dissolve ; in this the tissue is allowed to remain for 2 or 3 

 hours. Gentle heat is then applied to drive off the solvent 

 and melt the Paraffin, without injuring the specimen. The 

 mass is allowed to set, and gentle heat is again applied to 

 the vessel containing the mass to loosen it. The superfluous 

 Paraffin is trimmed and the mass fused on to the socket of 

 the rocking microtome. 



(vi.) RESIN AND WAX. 



Eesin, 3 ; Yellow Wax, 1 ; melt together. 



It is used for holding tissues (bone and teeth) whilst being 

 ground. 



Pieces are cut as thin as possible with a saw, and one side 

 is ground on an oilstone; the piece is then placed in the 

 Resin and Wax (liquefied by heat) and cemented on the 

 ground side to a piece of glass. When hard the tissue is 

 rubbed down to the required thickness on an oilstone. The 

 Eesin and Wax can be removed from the tissue by Oil of 

 Turpentine, in which both are soluble. 



PRESERVING SECTIONS. 



Sections are best preserved (previous to staining and 

 mounting) in 50 p. c. Alcohol, or in a mixture of Glycerine 

 and Thymol Water (1 in 1500) in equal volumes. If kept 

 long in strong Alcohol they are apt to shrivel. 



MANIPULATION OF SECTIONS. 



Thin sections which have been kept for some time in 

 Alcohol are apt to get folded or crumpled. If these be 



