[ 412 ] 



Clearinc! anb fiDounting Sections.'' 



WHEN sections have been properly stained, and it is desired 

 to preserve selected specimens as permanent preparations, 

 they must be mounted in some medium which will 

 interfere as little as possible with the structure of the tissues and 

 the colours that have been imparted to them. At the same time, 

 by being careful to make use of the most appropriate mounting 

 medium in each particular instance, much aid may be rendered in 

 studying the sections by the increased translucency afforded by 

 this means. Preparations of glycerine or of resinous substances 

 will be found in practice to meet all requirements, and it is often 

 advisable to mount specimens of the same object in both. 



Glycerine. 



Glycerine alone is very awkward to manipulate for permanent 

 preparations, though for temporary examination of vegetable tissues, 

 when somewhat diluted (two fluid parts to one of distilled water), 

 it is a very satisfactory medium. If, however, it be desired to gain 

 the fullest advantage from the use of glycerine it must be used in a 

 more concentrated form, either alone or with as little water as 

 experience shows to be desirable with the particular class of objects 

 in hand at any time. Each section, after being washed in dis- 

 tilled water to remove any alcohol, should be soaked in glycerine. 

 A ring of caoutchouc cement is then made in the middle of a 

 clean slide and allowed to dry. Next, place the section in position 

 within the ring, cover it with a drop of glycerine, give another 

 coating to the cement ring, and having gently breathed upon a 

 clean cover-glass, invert it on the object in such a manner as to 

 avoid introducing air-bubbles. The cover will soon be firmly 

 held by the cement, and any superfluous glycerine may after- 

 wards be washed off the slide by a gentle stream of water from 

 a wash-bottle. Finally, carefully brush round the cover another 

 ring of the cement, and, when this is properly set, the process may 

 be repeated with any finishing varnish that may be desired. If 

 the object is to be mounted in glycerine jelly, as much water as 

 possible should be drained away after placing the section in 



* From The Pharmaceutical [ournal and Transactions. 



