236 THE MICROSCOPE 



oil, and mount in dammar in the usual way.* Dr. Lewis f recom- 

 mends deep staining with an aqueous solution of the dye (^ to i 

 per cent.), and the subsequent removal of superfluous pigment, by 

 immersion for twenty minutes or so in an aqueous solution of 

 chloral hydrate (i to lo per cent.). The chloral is then removed 

 by washing in water, and the sections mounted in dammar or 

 balsam. 



Aniline Blue Black, i part ; water, 40 parts. Dissolve and 

 add rectified spirit, 100 parts. Keep in a stoppered bottle, filter a 

 few drops into a watch-glass, and add eight or ten times as much 

 alcohol to it. Stain the section from half to three minutes, and 

 mount in Canada balsam and benzole. 



Soluble Parme Fluid. — Obtained by treating diphenylate of 

 rose-aniline with sulphuric acid ; when dissolved in water in about 

 the proportion of i to 1,000, it gives a gorgeous blue, running into 

 violet, and colours the various tissues in a few minutes. They are 

 then to be washed in water, and either examined in glycerine, or, 

 after being deprived of their water by absolute alcohol, are to be 

 mounted in Canada balsam and benzole (Frey). 



Iron. — Dr. Frances E. Hoggan's method : — 



I. — Steep sections, fresh or hardened, in alcohol for about 

 five minutes. 



2. — Transfer to a watch-glass full of tincture of steel for 

 two minutes. 



3 — Remove into a 2 per cent, solution of pyrogallic acid 

 in alcohol ; and in one or two minutes, or when the desired 

 depth of colour has been attained, wash the sections in dis- 

 tilled water, and mount them in glycerine or glycerine jelly. 

 This is a very good method for staining cartilage, whether 

 normal or morbid. 



Blue Colours for Staining.— It is desirable in many cases to 

 make use of a blue fluid, especially for staining specimens injected 

 with carmine. Several methods are practical, as with sulph- 

 indigate of potash (so-called indigo carmine), with aniline blue, 

 and soluble parme. 



* Quart. Journal of Microscopical Science, Vol. XVL, p. 95. f Ibid, p. 73. 



