ON STAINING FLUIDS, AND STAINING. 115 



ensure absolute permeation by, and saturation with, 

 the paraffin. The blocks must be allowed to cool 

 thoroughly before they are removed from the 

 moulds; when removed, they may be pared down 

 to any size desired, and in such a manner that the 

 face of the embedded specimen, from which it is 

 intended to cut sections, shall be at the surface. 

 A sufficient body of paraffin must be left surround- 

 ing the specimen to ensure the necessary solidity 

 and equable support. Specimens thus embedded 

 and prepared for sectionising may be kept for an 

 indefinite time without alcohol, and used when 

 required. As they are perfectly embalmed and 

 preserved, the only necessary precaution is to 

 ensure absolute freedom from moisture in the 

 bottles or boxes in which the blocks are stored. 



The paraffin can be dissolved out of the sections 

 by means of chloroform, turpentine, turpentine and 

 oil of cloves mixed in equal proportions (this will 

 also clear the sections), or xylol; the latter being 

 of course preferable when the sections are to be 

 " cleared" in xylol and absolute phenol, and mounted 

 in xylol-balsam. When turpentine (only) is used, 

 and the sections are to be cleared in xylol and 

 phenol, they must be placed in absolute alcohol for 

 a short time to remove the turpentine, before being 

 immersed in the clearing fluid. 



Specimens can also be satisfactorily embedded 

 in paraffin by the following method (Giesbrecht* s) , 

 founded upon the rapid evaporation of chloroform, 

 and which, at the same time, is a speedy solvent of 

 paraffin. The specimens to be embedded having 

 been immersed to saturation in absolute alcohol are 

 next placed in chloroform ; a short time having 



