AND HOW TO TTSE IT. 233 



able, as clove-oil discharges the colour. This is a most valuable 

 dye, for in contact with certain tissues it gives a double stain. It 

 decomposes into two colours : one a r^^-violet, the other a blue- 

 violet, each of which acts on different tissues. It is useful for 

 hyaline cartilage ; the red-violet attaches itself to the matrix, and 

 the blue-violet to the corpuscles. For fresh tissues it also forms a 

 useful dye, and in the form of a one per cent, watery solution 

 it may be used instead of magenta. It stains certain parts a 

 beautiful violet, and is very useful for showing the corpuscles in 

 connective tissue, or the nuclei in fresh cells, or for mucous tissue. 

 It is best to mount in a saturated watery solution of potassic 

 acetate. 



Methyl-green.— This is a lighter green than the iodine, and is 

 used in the same manner. A 2 per cent, solution is usually 

 strong enough. This stain has a peculiar affinity for the heads of 

 spermatozoa. 



Spiller's Purple.— This is a very useful colour for double- 

 staining, and also for Bacteria. For double-staining, a 2 per cent, 

 solution in water is required, and the section must be very deeply 

 stained, as a great deal of the colour is washed out by the spirit. 

 For Bacteria a i per cent, solution, made with distilled water, is 

 best. At first, this colour is difficult to fix, but after numerous 

 trials we found it was less easily washed out if strong absolute 

 alcohol (795 sp.gr.) was used, than when methylated spirit was 

 employed. 



Green Colouration of the Nuclei. — To obtain this, Tafani 

 employs a fluid containing three or four parts of a saturated 

 watery solution of aniline-blue to some six or seven parts of a 

 saturated watery solution of picric acid. 



Rose-aniline Hydro-chloride. — This is useful for double and 

 treble staining ; and for this purpose a strong solution must be 

 made in rectified spirit. Place some of the crystals in a glass 

 mortar, and rub up with a little spirit; add spirit until all the 

 crystals are dissolved. This will do for ordinary staining pro- 

 cesses. It is also used in a special manner for the Tubercle 

 Bacillus, and the method of makin^r the stain is as foUovVS :— Take 



