ON STAINING FLUIDS, AND STAINING. 103 



described in the chapter on Mounting. All 



tissues, sections, and specimens, to be mounted in 

 pure glycerine, should be subjected to a prolonged 

 immersion in glycerine and distilled water, the pro- 

 portion of the glycerine to that of the water being 

 gradually increased every day or two until pure has 

 been substituted for diluted glycerine. Great care 

 must be taken that the specimen shall be thoroughly 

 saturated with the glycerine before mounting it 

 therein. 



This soaking may be done either in watch-glasses 

 or very small staining saucers, and many specimens 

 or sections can thus be immersed together. In 

 order to prevent the glycerine from absorbing 

 moisture from the atmosphere, and to ensure clean- 

 liness, the saucers should be placed under bell- 

 glasses whilst the soaking is in progress. This 

 process, moreover, prevents the serious shrinkage 

 which too frequently results, especially with delicate 

 tissues and specimens, which have been mounted in 

 glycerine without previous saturation therewith. 

 Tissues, sections, delicate marine animals, insects, 

 &c., which are to be mounted in glycerine may be 

 preserved therein until required. 



Glycerine undoubtedly affects logwood stainings 

 adversely, but if slightly acidulated with acetic acid 

 it does not attack 1 carmine or picro-carmine. 



Acetate of Potash. Make a saturated solution 

 in distilled water, it may be so used or diluted if 



1 Farrant's medium is preferable for the mounting of speci- 

 mens stained by either of these. It is advisable to rather 

 overstain and to soak the specimens in the medium for two 

 or three days, in order to extract the superfluous stain before 

 mounting them. 



