TEXT-BOOK OF BACTERIOLOGY. 53 



bacilli, for instance, take the color very unwillingly, while several 

 saprophytic bacteria, the hay-bacillus, the BacUlus megaterium, 

 etc., are far more easily managed. Lastly, there are a few micro- 

 organisms into whose spores even the ordinary staining solutions 

 readily penetrate. 



As regards this last point, it is necessary to be guarded against 

 deceptions. The spore-formation is a gradual process. It has its 

 preliminary stages, which display smaller or larger granules in the 

 bodj- of the protoplasm. These things take the stains sometimes 

 more readily than the surrounding parts, and when they are of a 

 certain size thej' may easilj' be mistaken for fully -developed spores. 

 Their nature is not yet jjroperly understood, but they certainly are 

 not fully-formed spores. 



They are incapable of the genuine spore-staining; Aet that they 

 differ considerably from the other contents of the cell is clearly 

 seen by the fact that we can occasionally succeed in demonstrating 

 them by means of a staining process described by Ernst. He flrst 

 treats the preparation with warm (not hot) alkaline methyl-blue 

 solution, washes with water, and then stains again with aqueous 

 solution of Bismarck-brown. The sporogenic granules then appear 

 in blue on a brown background. 



The second peculiar staining process which it is desirable to 

 consider, because, like the spore-staining, it is only applicable in the 

 case of cover-glass preparations, is the method, already mentioned, 

 introduced by Loffler for displaying the flagella of the motile 

 bacteria. 



The principal measures to be employed with the mordant solu- 

 tions have alreadj' been noted, as well as their composition. Let a 

 few drops of the mordant fall upon the preparation on the cover- 

 glass, which must then be warmed immediately over the flame till 

 vapors arise or the solution begins to boil. The mordant must 

 now be washed away from all parts of the preparation with water, 

 and even from the edges wiped away with blotting-paper. Wher- 

 ever traces of the mordant which have not been absorbed by the 

 bacteria are allowed to ^remain, troublesome deposits are sure to 

 afterward arise. On this account, in making a preparation it is 

 necessary to be careful that the layers be spread over the glass as 

 thinly and transparently as possible. When this step is accom- 

 plished the staining proper begins, for which anilin gentian-violet, 

 or anilin-fuchsin, or better still, carbol-fuchsin, can be employed. 

 Loffler himself prefers to use here his latest coloring mixture, which 

 has already been mentioned. He takes 100 c.cm. of 1^ soda-lye solu- 

 tion, and to this 4 or 5 grams of gentian-violet, fuchsin, or methyl- 



