216 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



by boiling, is poured while still hot into a bottle in which crystals of 

 ammonia-alum have been placed in quantity more than sufficient to 

 saturate the fluid. The bottle is well shaken, and then allowed to cool. 

 To 10 ccm. of this fluid, 10 ccm. of a freshly made 10 p.c. solution of 

 tannic acid and 5 ccm. of carbol-fuchsin are added. The mixture is 

 filtered. The cover-glasses are washed in strong hydrochloric acid, and 

 when removed therefrom are wiped with a clean cloth and thoroughly 

 heated over a Bunsen burner. The traces of acid left on the slips help 

 to prevent precipitation of mordant or stain. The bacilli are placed on 

 the cover-slip and fixed. The mordant is then filtered, poured on the 

 film, and heated until steam is given off. The heating, without boiling, 

 should be continued for about three minutes. The preparation is then 

 washed in distilled water, and, after adding the stain, is heated in 

 the same way for three or four minutes. The stain is marie by adding 

 1 ccm. of a saturated alcoholic solution of gentian-violet to 10 ccm. of 

 a saturated solution of ammonia-alum. This is filtered and poured on 

 the preparation. 



Fig. 34. 



Double Staining of Spores and Bacilli.* — E. Greig Smith advises 

 the following modification of Klein's method for staining spores. Four 

 drops of normal saline solution are pipetted into a small test-tube, and 

 the spore-bearing material is rubbed up with this until a homogeneous 

 suspension is obtained. Four drops of carbol-fuchsin are pipetted into 

 the tube, and the mixture shaken. A plug of cotton- wool is inserted, 

 and the tube placed in a beaker of boiling water. The boiling is con- 

 tinued for a quarter of an hour, when the tube is taken out and shaken. 

 A loopful of the bacterial suspension is withdrawn and spread uniformly 

 over a cover-glass, which is dried either in the air or high over a Bunsen 

 flame. The film is next fixed by passing the cover-glass thrice through 

 the flame in the usual manner. The bacilli are decolorised in methy- 

 lated spirit containing 1 ■ 5 p.c. by vol. of strong hydrochloric acid. 

 When the film appears colourless, the cover-glass is withdrawn and the 

 alcohol removed with water, after which the film is stained with carbol- 



• Proc. Linn. Soc. N.S.W., xxv. (1900) pp. 394-7. Cf. this Journal. 1899, p. 346. 



