340 Veraniis Alva Moore 



intimate relation that exists between methods and resnlts in 

 the study of the morphology of bacteria will undoubtedly ex- 

 plain many of these discrepancies. In the endeavor to bring 

 out more fully the character of the flagella of the three species 

 of bacteria in question, it is desirable, on account of their inti- 

 mate association with the development of our knowledge of 

 flagella, to consider first, in a general manner, the methods 

 that have been proposed for their demonstration and to give a 

 brief resume of our knowledge of these filaments and their 

 accepted significance. I furthermore wish to acknowledge 

 my indebtedness to the various writers on this subject for 

 many valuable suggestions. 



A SUMMARY OF OUR RECORDED KNOWI,EDGE OF THE FI^AGEUvA OF 

 MOTILE BACTERIA. (l) METHODS FOR THEIR DEMONSTRATION. 

 (2) THEIR CHARACTER AND SIGNIFICANCE. 



Cohn' and Koch^ appear to be the first who stained the 

 flagella. The methods by which they demonstrated the ex- 

 istence of these filaments have not been successfully applied 

 to the smaller and especially the parasitic organisms. Al- 

 though our instruments and methods have been much im- 

 proved since Dallinger^ and Drysdale made their observa- 

 tions, the detection of the flagella on living, moving bacteria 

 is a result which has rarely if ever been attained with the 

 small and pathogenic bacteria. From 1877 to 1889 no 

 further knowledge of these filaments appears to have been 

 acquired. 



In 1889 Loeffler" succeeded in formulating a method by 

 which he could stain the flagella on a considerable number of 

 bacteria. The process, however, was not satisfactory, and a 

 year later he published a second method^ which has since 

 borne his name, and which he believed would, if properly 

 carried out, be applicable in .staining the flagella on all the 

 motile bacteria, 



A few other methods* have been proposed, but lyoeffler's 



*In ail article'2 publislied in the American Monthly Microscopical 

 Journal, (January, 1891), I reviewed the various methods that had been 

 used in demonstrating the flagella on motile bacteria up to that time. 

 See Literature, No. 5, 7, 10, and 11, at the close of this article. 



