154 BACTERIOLOGY. 



Absolute alcohol 100 c.c. 



Hydrochloric acid 3 c.c. 



In this solution it is placed, bacteria up, and the 

 vessel is tilted from side to side for about one minute. 

 It is then removed, washed in water, and stained with 

 the methylene-blue solution. The spores will be stained 

 red and the body of the cells will be blue. 



Moellek's Method for Staining Spores. — A 

 method that has recently been published by Moeller 

 is designed to favor the penetration of the coloring- 

 material through the spore membrane by macerating 

 the spores in a solution of chromic acid before staining 

 them. It is as follows: 



The cover-slips are prepared in the usual way, or the 

 fixing may be accomplished with absolute alcohol in- 

 stead of high temperatures. The preparation is then 

 held for two minutes in chloroform, then washed off in 

 water, then placed for from one-haK to two minutes in 

 a 5 per cent, solution of chromic acid; again washed off 

 in water, and now stained in carbol-fuchsin. In the 

 process of staining, the slip is taken by the corner with 

 the forceps, and carbol-fuchsin is dropped upon the 

 side containing the spores. It is then held over the 

 flame until it boils, and then held some distance above 

 the flame for one minute. The staining-fluid is then 

 poured off and the preparation is completely decolorized 

 in 5 per cent, sulphuric acid, again washed off in water, 

 and finally stained for thirty seconds in the watery 

 methylene-blue solution. The spores will be red, the 

 body of the cells blue. 



In this method the object of the preliminary ex- 

 posure to chloroform is to dissolve away any crystals 

 of lecithin, cholesterin, or fat that may be in the pre- 



