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. 



KOERNER and FISCHER (quoted from Encycl. mik. 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 f uchsin. Warm, let it act for 

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

 fuchsin. 



Similarly ELLIS (Centralb. Bakt., xxi, 1903, p. 241 ; Journ. 

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

 1 part to 75 of alcohol and 75 of water. 



PEPPLER (Centralb. Bakt., xxix, 1901, p. 376 ; Zeit. wiss. 

 Mik., 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. 



Kossi (Arch, per le Sc. med., xxiv, 1900, p. 297 ; Zeit. wiss. 

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

 25 grins, of tannic acid in 100 of caustic potash of 0*1 per 

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

 carbol-fuchsin, 289. Cover-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 Centralb. Bakt., xxxiii, 1903, p. 572 (Zeit. iviss. Mik., 

 xix, 1903, p. 517). 



GEMELLI (Centralb., xxxiii, 1903, p. 316 ; Zeit. wiss. 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 PITFJELD is described by KENDALL, Journ. 

 app. 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 

 solution of alum. 



