404 E. HANBURT HANKIN. 



although this solvent is quite capable of washing out all the 

 colour from nuclei, connective tissue, &c. 



Not only clove oil, but also other clearing reagents, such as 

 benzine, xylol, creosote, aniline, and cedar oil have a greater or 

 less power of fixing the colour in the bacteria, though several 

 of them can dissolve the aniline dyes freely. 



Sections stained by any of these methods, quickly dehydrated 

 and cleared, can then be washed for a longer time in alcohol, 

 without the dye leaving the bacteria^ than can sections which 

 have been taken direct from the dye into spirit. I even found 

 that clearing the tissue before staining, and then washing in 

 alcohol, would slightly improve the result in some cases. 



Concerning this method of staining it may be remarked 

 that, firstly, a mixture of methyl blue and eosin has scarcely 

 any staining power. If the sections are put into the dye 

 after the addition of the eosin no result is obtained, and 

 consequently it is immaterial how long the sections are left in 

 the mixed staining solution. Secondly, the eosin solution is 

 much stronger than that in general use. If a section is 

 stained in methyl blue, and then placed in a saturated alcoholic 

 solution of eosin, as here used, in a very few seconds all the 

 blue colour is turned out, and the section stained of a uniform 

 red tint ; but in this method the presence of the methyl blue 

 in solution seems to protect the tissue from the eosin. Thirdly, 

 when eosin and methyl blue solutions are mixed some of the 

 methyl blue is precipitated, and after some time will be found 

 sticking to the sides of the containing vessel. Fourthly, if a 

 greater quantity of the eosin solution than that above men- 

 tioned is employed, instead of a preponderance of red in the 

 resulting stain, it will be found that the methyl blue has com- 

 menced to stain the background besides the nuclei, and the 

 whole section will have a purplish colour. Fifthly, if the con- 

 ditions of solution of the dyes are reversed, and alcoholic 

 methyl blue is added to watery solution of eosin, no staining 

 effect is produced, unless the saturated eosin is diluted with 

 about five times its bulk of water. By this method the bacteria 

 are stained slightly better than in the manner above described. 



