MICROSCOPICAL TECHNIQUE. 225 



three minutes ; after which they are ready for immediate observa- 

 tion (for example, blood, etc.), or after dehydrating, clearing, and 

 mounting as usual. 



Borofuchsin as a Stain for Tubercle Bacilli.^— Prof. Lubimoff 

 describes in the Meditsinkoe Obozrenie a new stain for tubercle 

 bacilli, which he calls Borofuchsin. It consists of 



Fuchsin ... ... ... 7 J grains. 



Boracic Acid ... ... 7^ grains. 



Absolute Alcohol ... ... 4 drachms. 



Distilled Water ... •••5 drachms. 



When prepared in this way, it has a slightly acid reaction. It 

 is quite clear and not liable to be spoilt by being kept, and conse- 

 quently it is always ready for use. The sputum is dried on a 

 cover-glass, and stained by being heated in contact with the boro- 

 fuchsin for one or two minutes. The stain is then washed out by 

 treatment with dilute sulphuric acid. The specimen is then washed 

 with alcohol, and subsequently immersed for half a minute in a 

 saturated alcoholic solution of methylene blue. After being washed 

 in distilled water and dried, the examination of the specimen is 

 made in oil of cedar or in a solution of Canada balsam. In 

 exactly the same way sections of tuberculous organs may be stained 

 after hardening in spirit, only in such cases the steps of the opera- 

 tion must be somewhat more prolonged. The main difference 

 between this and other staining processes for Koch's bacilli is that 

 when borofuchsin is used the process of washing it out with sul- 

 phuric acid is an almost instantaneous one. All other bacilli are, 

 as when other stains are used, rendered colourless and invisible, 

 the tubercle baciUi alone being seen. 



For mounting preparations cleared with chloral hydrate which 

 it is desired to retain in their transparent condition, Geoffrey 

 suggests (Journ, de Botanique^ vii., 55, 1893) a solution of 3 to 4 

 grms. of pure glycerine in 100 grms. of 10 per cent, chloral 

 hydrate. This can be used like glycerine, with the added conven- 

 ience that it hardens at the edge of the cover, so that the cover 

 can be cemented without tedious cleaning. 



* Lancet, 



