232 ' THE MICROSCOPE 



Orchella, or French Archil : Staining with the extract. — Wedl 

 uses this substance, which, after the loss of the ammonia, is dis- 

 solved in 20 cc. of absolute alcohol, 5 cc. of acetic acid, and 

 40 cc. of distilled water, so as to make a saturated solution. Pro- 

 toplasm and matrix are coloured red. Sections hardened in 

 Muller's fluid, chromic acid, or methylated spirit, must be washed 

 in distilled water ; touch the section on the back of the hand or 

 blotting-paper to get rid of the water ; apply a few drops of the 

 staining fluid to the section, and mount. Fresh pathological 

 formations stain well. 



Gentian Blue. — Where Bacteria form the subject of observa- 

 tion, this stain must be genuine. That sold by Messrs. Hopkin 

 and Williams is recommended by Dr. Gibbes. A half per cent, 

 solution is the best strength to use. 



Iodine G-reen is especially useful for observing the nuclei of 

 osseous tissue. In growing bone it colours the unossified carti- 

 lage, giving a very striking result. It stains mucous glands green. 

 A saturated watery solution should be made with distilled water ; 

 when required, make a i per cent, solution, and filter. This is 

 really a multiple stain, as it gives different tints of the same 

 colour. It stains rapidly, and cannot be removed by washing. 

 The staining process should be carefully watched, and the sec- 

 tions removed when the required tint is gained. Mount in 

 dammar, etc. Do not leave the stained sections long in spirit, 

 which partially removes the dye. For botanical work use an 

 alcoholic solution of iodine green — 3 grains to the ounce of 

 alcohol. 



Methyl-blue, for examining bacillus in the breath of phthisical 

 subjects. It is used as a contrast or ground-stain for Tubercle 

 Bacillus. A strong, nearly saturated, solution is required ; a good 

 proportion (r drachm to the ounce) of rectified spirit must be 

 added to make it keep. In using, stain the tissue deeply, and 

 wash away the superfluous pigment in water acidulated with acetic 

 acid. The acetic acid dissolves out much of the pigment, and 

 the washing must be continued till the proper tint is obtained. 

 The sections must then be thoroughly washed in water, and 

 mounted in glycerine or Farrant's solution. Dammar is unsuit- 



