182 IVAN V. SHUNK 



For certain organisms Loeffler claimed that no. 1 was suffi- 

 cient, while in other cases varying amounts of the corrective 

 solutions had to be added, according to the organism studied. 



Since this method was devised by Loeffler, a number of modifi- 

 cations have come into use, one of the first being the abandon- 

 ment of the corrective solutions, as their use was found to be 

 unnecessary. Loewit (1896) modified the process by using a 

 copper sulphate-tannic acid mordant instead of the ferrous 

 sulphate-tannic acid. Another modification was made by Bunge 

 (1894) who used ferric chloride in the mordant instead of ferrous 

 sulphate. The use of ferric chloride in the mordant, in part, in 

 my new modification is an application of Bunge's modification. 



As a usual rule, flagella staining has been a more or less hit 

 and miss process. In text-books on bacteriology it is in sub- 

 stance so acknowledged, as by Park and Williams (1914), who 

 state that with the method advised "frequently the flagella appear 

 well stained but often the process has to be repeated a number of 

 times." Giltner (1916) states that "failure to make a good 

 flagella stain with any method is no sign that the student is not 

 a good workman, nor is success the sign of a good bacteriologist." 



I have believed that at least a part of the difficulty of staining 

 flagella has been due to difficulties in fixing the bacteria on the 

 cover-glass. In most processes it is advised to heat the cover- 

 glass preparation by passing it through the flame or by holding 

 it over a flame, but it is sometimes added that care must be 

 taken not to overheat. It is a difficult matter always to heat to 

 the same extent by passing a cover-glass through a flame, and 

 furthermore the flagella of certain bacteria might be overheated 

 more readily than those of certain others. 



As the fixing by heat has been one of the doubtful procedures, 

 I have experimented with several different chemical solutions 

 in order to accomplish the fixing without heat. Two solutions 

 especially have been used, both of which have given good results, 

 the preference being perhaps for the first, although both are 

 effective. These solutions are made up as follows: 



