l894-] NEW-YORK MICROSCOPICAL SOCIETY, 7 



by Loeffler in his second method,' and modified as already sug- 

 gested, are now made in the laboratory of Micro-Biology at Co- 

 lumbia College as follows : 



Mordant. — To lo c.c. of solution of tannin (20 per cent in 

 water) add commercial solution of iron acetate, drop by drop 

 (about 5 cc), until a violet-black is produced without precipi- 

 tate. Then add 5 to lo drops of acetic acid and 4 c.c. of solution 

 of carbolic acid (12 per cent in water), and filter. With ordinary 

 protection from the air, the solution is stable for a long time. 



Loeffler also adds i c.c. of fuchsin solution to the mordant, 

 and so also NicoUe and Morax, with the special purpose to insure 

 staining of the cilia. As my own object is the more general one 

 of effecting a uniform and harmonious coloration of the enfire 

 bacterium, I find the results under better control by confining 

 the anilin color to the colorant proper. 



Colorant. — To 100 c.c. of anilin water add solution of sodium 

 hydrate (i per cent in water), drop by drop (about 5 c.c), until 

 a neutral reaction is obtained with test papers. Then add \ 

 gramme of fuchsin and shake until solution; but filter every time 

 just before using. From time to time, as the solution loses color 

 by decomposition, add a little more fuchsin and shake up before 

 filtering. 



In the original process, with exclusive object of staining cilia, 

 Loeffler uses 4 grammes of fuchsin, and Nicolle and Morax, 

 Zielil's fuchsin — both solutions being saturated with stain and 

 opaque. On films prepared by my method, fixed and dried with 

 little or no heat, the results appear more satisfactory with an 

 alkaline solution like that of Loeffler, though containing but 

 one-eighth of the amount of stain he prescribes, brightly colored 

 but transparent. 



A supposed improvement of Loeffler's process has been ad- 

 vanced by A. P. Brown, ^ who substitutes as mordant a cold 

 alcohol solution of tannin and anilin oil, in which- the dried 

 bacteria film is to be immersed for two to five hours or over night. 

 This method also I have tried for about a month, and, although 

 it often yields excellent results, it has appeared to be less certain 

 and uniform than the hot mordant recommended by Loeffler. 



1 Joar. de Micrographie, xv. (1891), 269. 



2 The Observer, iii. (1892), 29s, and Jour. Roy. Mx. Soc. (1893), 268. 



