METHODS FOR STAINING FLAGELLA. 155 



paration, and which when stained might give rise to 

 confusion. 



It must be remembered that there are conspicuous 

 differences in the behavior of spores of different bacteria 

 to staining-methods. Some stain readily by either of 

 the methods especially devised for this purpose, while 

 others can hardly be stained at all, or only with the 

 greatest difficulty, by any of the known processes. 



LCEFFLER'S METHOD FOR STAINING FLAGELLA. 

 For the demonstration of the locomotive apparatus pos- 

 sessed by motile bacteria we are indebted to Loeffler. 

 By a special method of staining, in which the use of 

 mordants played the essential part, he has shown that 

 these organisms possess very delicate, hair-like appen- 

 dages, by the lashing movements of which they propel 

 themselves through the fluid in which they are located. 

 The method as given by Loeffler is as follows : 



It is essential that the bacteria be evenly and not 

 too numerously distributed upon the cover-slip. The 

 slips must therefore be carefully cleansed. (See Loeffler's 

 method of cleaning cover-slips.) Five or six of the 

 carefully cleansed cover-slips are to be placed in a line 

 on the table, and on the centre of each slip a very small 

 drop of tap-water is placed. From the culture to be 

 examined a minute portion is transferred to the first 

 slip and carefully mixed with the drop of water; from 

 this mixture a small portion is transferred to the second, 

 and from the second to the third slip, and so on in this 

 way insuring a dilution of the number of organisms 

 present in the preparation. 



These slips are then dried and fixed in the ordinary 

 way. They are next to be warmed in the following 

 solution : 



