402 E. HANBURY HANKIN. 



(3) A pipette to hold the above. A test-tube fitted up as a 

 wash bottle is very convenient for holding the eosin. 



(4) Absolute alcohol, which must be used in a capsule pro- 

 vided with a cover, to prevent the access of watery vapour from 

 the air. Every precaution should be taken to keep the alcohol 

 as free from water as possible. 



(5) Benzine and clove-oil mixture, made by mixing equal 

 volumes of benzine and oil of cloves, and addmg sufficient abso- 

 lute alcohol to dissolve the turbidity that appears on shaking 

 together the above reagents. 



(6) Oil of cloves, which must be fresh and nearly colourless. 

 By exposure for a few hours to light and air oil of cloves loses 

 a great deal of its power of dissolving the aniline colours. 



(7) Benzine. This may be replaced by xylol or cedar oil. 

 Modus Operandi." — The sections are taken from spirit 



and placed in the methyl blue solution. Immediately the 

 eosin is dripped in from the pipette. About equal parts of the 

 eosin and methyl blue solutions are employed. If too much 

 eosin is used the background of the section will have a dull 

 purplish tinge, contrasting badly with the blue-tinted bacteria ; 

 while if too little eosin has been dropped in its red shade is 

 scarcely visible. 



By adding eosin to the solution its power of dissolving 

 methyl blue is diminished. Part of the excess is precipitated 

 in the form of a granular deposit ; part of it combines with the 

 tissue in the form of stain. The precipitate thus rapidly 

 formed is readily dissolved by the alcohol used in dehydrating, 

 and never spoils the appearance of the specimen. As soon as 

 the eosin has been added the sections are removed one by one 

 to absolute alcohol, shaken about in it for a few seconds, and 

 then placed in the benzine and clove-oil mixture. 



The sections are washed in this till the effects of the eosin 

 begin to be apparent, then washed rapidly in another capsule 

 of the same mixture, spread out on a section lifter, placed in 

 benzine, and mounted. If, however, they are not sufficiently 

 decolorised they should be removed to oil of cloves, which will 

 readily dissolve the excess of methyl blue. If the red tint of 



