482 CHAPTER XXXVI. 



becomes red-brown, when it is shaken up and filtered on to 

 the cover-glass and allowed to act for a minute. The cover- 

 glass is then mopped up and dried, and stained with carbol- 

 gentian. 



KoERNEE and Fischee (quoted from Encycl. mile. Techn. 

 p. 514) make the mordant with 2 parts of tannin, 20 of water, 

 4 of ferrous sulphate solution of 1 : 2 strength, and 1 of 

 saturated alcoholic solution of fnchsin. Warm, let it act for 

 a minute, rinse and stain with anilin-water-fuchsin, or carbol- 

 fuchsin. 



Similarly Ellis [Gentralb. Bakt., xxi, 1903, p. 241 ; Juurn. 

 lioy. Mic. Soc, 1904, p. 249), but staining with Siiureviolett, 

 1 part to 75 of alcohol and 75 of water. 



Pbpplee {Gentralb. Bakt., xxix, 1901, p. 376 ; Zeit. wiss. 

 Mih., xviii, 1901, p. 222) makes the mordant with 20 parts of 

 tannin in 80 of water, and 15 parts of 2'5 per cent, chromic 

 acid added gradually. This mordant will keep for months. 



Eossi [Arch, per le 8c. med., xxiv, 1900, p. 297 ; Zeit. wlss. 

 Mih., xviii, 1901, p. 226) takes for the mordant a solution of 

 25 grms. of tannic acid in 100 of caustic potash of O'l per 

 cent., which will keep indefinitely. The stain is Ziehl's 

 carbol-fuchsin, § 289. Oover-glasses are prepared with a 

 drop of culture, dried, and treated with 1 drop of the 

 mordant and at the same time 4 to 5 of the stain, allowed 

 to remain for 15 to 20 minutes, washed, and mounted. See 

 also Gentralb. Bakt., xxxiii, 1903, p. 572 {Zeit. wiss. Mik., 

 xix, 1903, p. 517). 



GrEMELLi {Gentralb., xxxiii, 1903, p. 316 ; Zeit. iviss. Mik., 

 xix, 1903, p. 516) mordants for 10 to 20 minutes in 0-025 per 

 cent, permanganate of potash, rinses and stains for 15 to 30 

 minutes in a mixture of 20 parts 0'75 per cent, aqueous 

 solution of calcium chloride and 1 part of 1 per cent, neutral 

 red solution. 



A method of Pitpield is described by Kendall, Journ. 

 apj). Mic, V, 1902, p. 1836 {Journ. Roy. Mic. Soc, 1902,p. 502). 

 The mordant consists of 10 parts of 10 per cent, tannin solu- 

 tion, 5 parts of saturated sublimate solution, 5 of saturated 

 solution of alum, and 5 of carbol fuchsin. Mordant for a 

 minute with heat, and stain with a mixture of 2 parts satu- 

 rated aqueous solution of gentian violet with 10 of saturated 

 solutioii of alum. 



