NEW METHODS OF USING THE ANILINE DYES. 403 



the background is not sufficiently pronounced they may be 

 treated for a minute or less with eosin dissolved in clove oil, 

 afterwards washed in benzine and clove-oil mixture, lastly in 

 benzine, and then mounted. 



The whole process does not take much more than a minute, 

 of which about twenty seconds are occupied in adding the 

 eosin solution to the methyl blue. The dehydrating in alcohol 

 should be accomplished as rapidly as possible. 



Sections stained in this manner show the bacteria stained 

 blue; the nuclei are similarly coloured, but of a lighter shade, 

 the eosin has stained the red blood-corpuscles orange, and the 

 background of the tissue is of a rose-red tint. 



Ganglion cells are stained purple if the section has not had 

 too much of the colour removed. Besides the blood-corpuscles 

 eosin can stain several other things of a yellow or orange tint, 

 and if these structures have also an affinity for methyl blue the 

 two dyes combine, giving a bright green shade. Haemoglobin 

 crystals and sometimes red blood-corpuscles are thus stained. 



In sections through the lung of a sheep which had suffered 

 from foot-and-mouth disease this eosin and methyl blue method 

 showed large amorphous caseous deposits of a bright emerald- 

 green colour, while other methods of staining failed to 

 diflFerentiate them. 



Sections of the lung of another sheep, which contained 

 encysted thread-worms, showed within their rose-red epidermis 

 the protoplasm of the nematodes stained green, and their 

 nuclei of a purple tint. 



Sections through a congested spleen showed orange-red 

 blood-vessels on a background of blue and green nuclei almost 

 as well as an injected specimen. 



While oil of cloves is generally used to help the alcohol in 

 taking the excess of colour out of a section, I, on the contrary, 

 use it for keeping the colour in, so far as the bacteria are con- 

 cerned ; for bacteria stained as here described would rapidly 

 become invisible if left for long in the more powerful solvent, 

 namely, the alcohol ; and sections may often be kept inde- 

 finitely in oil of cloves without the bacteria losing their stain, 



