BY R. GREIG SMITH. 395 



noted that it was much easier to kill bacteria and spores when 

 they were in the moist condition than when they had been dried, 

 and from this he reasoned that it would be much easier for the 

 stain to get through the moist than through the dried spore-case. 

 Accordingly he stained first and fixed afterwards. 



His procedure is as follows : — A platinum loop is filled with a 

 culture of the bacillus grown upon potato for 24 hours (at 37° C), 

 and this is introduced into a small quantity — say, two or three 

 drops — of normal saline contained in a watch-glass. The culture 

 is stirred in the saline until a homogeneous suspension is obtained. 

 An equal number of drops of carbol-fuchsin is added, and the two 

 fluids are thoroughly mixed. The watch-glass is placed high over a 

 micro-chemical burner so that the'heat applied is just sufficient to 

 cause a slight vapour to hover over the surface of the fluid. A 

 larger watch-glass is placed over the first to keep out the dust 

 and to enable one to judge the intensity of the heating. There 

 should be just a slight Him of condensed water upon the covering 

 glass. At the end of six minutes the watch-glass is taken from 

 the burner and allowed to cool for a few moments. The bacilli 

 and spores which have precipitated more or less are again distri- 

 buted in the stain by imparting a rotatory motion to the cover- 

 glass. A loop of the suspension is spread over a clean cover-glass 

 and allowed to dry in the air. The film is fixed by passing it 

 twice through the flame. The bacilli are then decolorised by 

 immersing the cover-glass in 1% sulphuric acid for one or two 

 seconds, after which the acid is washed off with water and the 

 bacilli counter-stained in dilute watery-alcoholic methylene-blue 

 for three or four minutes. The Him is washed in water, dried 

 and mounted in balsam. After this treatment the spores appear 

 red, the bacilli blue. 



The method as recommended by Klein is excellent as far as 

 the principle is concerned, but the details might be altered with 

 advantage. Some spores, instead of staining red, show only a 

 pink margin. Klein does not push the staining process far 

 enough, and indeed it is hardly possible to do so when a watch- 



