ON STAINING FLUIDS, AND STAINING. 97 



When, however, it is not desired to mount with 

 the section its surrounding and supporting celloidin, 

 Turpentine will be found the best solvent of that 

 material as well as of paraffin when that has been 

 used as the embedding agent. 



Turpentine should not be used for specimens or 

 sections which have been hardened or preserved in 

 alcohol or methylated spirit, as it has great shrink- 

 ing power. It will be found very useful for entomo- 

 logical preparations, and especially for insects with 

 very hard integuments ; these must be left to soak 

 in turpentine until they are cleared, but small and 

 delicate insects can be better cleared in xylol and 

 phenol. Turpentine is also a good clearing agent 

 for vegetable specimens of a woody nature. All 

 specimens or sections cleared by turpentine should 

 be mounted in Canada balsam, hardened and re- 

 dissolved in turpentine, and carefully filtered. 



Oil of Cloves has some advantages over all other 

 clearing agents (xylol and phenol excepted), and is, 

 perhaps, the most universally used. It combines 

 well with both alcohol and balsam and does not 

 shrink the specimens as turpentine does ; but 

 "clearing" with this oil involves its removal by 

 placing the sections in turpentine after they have 

 been cleared, because if the clove oil remains in the 

 specimens or sections, although it is miscible with 

 the balsam, it prevents the balsam from hardening 

 and so renders the preparations unsafe. 



Sections cut from specimens which have been 

 embedded in celloidin and which it is desired to 

 mount so embedded must not be cleared in oil of 

 cloves, as it dissolves the celloidin at once ; it is 

 therefore a good clearing agent when it is desired to 

 7 



