STAINING AND MOUNTING FROZEN SECTIONS 165 



Where very rapid work is required it is not advisable to stain 

 the sections in the method described in the next paragraph, since 

 it takes too long. A simple stain (such as watery methylene blue) 

 is used, the staining being done on the slide, a cover-glass applied, 

 and the excess of stain removed by means of blotting-paper. It 

 is necessary to acquire a considerable amount of experience of 

 this method before using it for diagnosis, as the appearance 

 of sections prepared in this way and examined in a watery fluid is 

 very different from that which they have when double-stained and 

 mounted in balsam. 



STAINING AND MOUNTING FROZEN SECTIONS 



These processes are best carried out in watch-glasses. No 

 attempt will be made to describe the methods by which frozen 

 sections may be stained for the purposes of bacteriological research, 

 for they are not so suitable as paraffin sections for this purpose. 

 We shall describe the process of staining in haematoxylin (with 

 or without eosin as a counterstain) and mounting in balsam. 



The requisites are : Five watch-glasses containing respectively 

 haematoxylin, watery solution of eosin (about i per cent.), alcohol 

 (50 per cent.), absolute alcohol, and clove oil ; a saucer or other 

 vessel containing water to which a few drops of ammonia have 

 been added ; several strips of thin writing-paper, each about 

 I inch wide and 2 inches long ; some needles, which may be 

 mounted in handles ; slides, cover-glasses, and balsam. 



A section is to be removed from the bowl of water in which it 

 is floating by means of one of the strips of paper ; this must be 

 inserted under it, and the section " pinned " in place upon it by one 

 of the needles. A special section -lifter may be used, but is not so 

 good. It is then transferred to the watch-glass containing the 

 haematoxylin solution, and the staining process is allowed to go 

 on for a minute or two, a fresh section being manipulated whilst 

 it is taking place. The first section is then removed in the same 

 way as before, and placed in the water containing the ammonia; 

 it soon turns blue, and when this is the case it is ready to be 

 transferred to the eosin, then into the dilute alcohol, the absolute 

 alcohol (where it should remain for a minute or more), and finally 

 into the oil of cloves. It is then ready to be mounted in balsam" 

 A convenient way in which a section can be transferred to a slide 

 is as follows : The section is carefully spread out whilst in the 



