The Character of the Flagella 355 



although a single bacillus which exhibits this uniform radia- 

 tion of motile appendages is rarely observed in stained prepa- 

 rations. The flagella are usually more or less wavy, and it is 

 the rule, though it has many exceptions, that the waves in a 

 single flagellum are uniform. 



I have studied very carefully the flagella on several hog 

 cholera bacteria. These were obtained from different sources 

 (outbreaks of hog cholera) and a few of them exhibited slight 

 variations in their biological characters and more marked dif- 

 ference in their virulence. So great have been these varia- 

 tions in a few cases that the bacteria have been deemed modi- 

 fied forms. I have also studied a larger number (about 20) of 

 colon bacteria isolated from variously diseased organs of differ- 

 ent animals and from the human intestine. These have also 

 shown a marked difference in their properties. The two cul- 

 tures more specifically described represent (i) the more typical 

 form (2) a somewhat modified form. Of the typhoid bacteria, 

 only two cultures have been at my disposal. All of these 

 bacteria have been carefully studied and their identification 

 clearly established. In these examinations I have been un- 

 able to detect any constant, specific difference in the character 

 of the flagella on the germs from the different cultures of the 

 same species. On this account bacteria from only two cultures 

 of each species will be considered in the more specific descrip- 

 tion of the flagella. 



The flagella on Bacillus cholera siiis. (Plate i. Fig. i.) 

 Ci) A culture of hog cholera bacteria which was obtained from 

 a pig that died in an outbreak of hog cholera in the State of 

 Illinois in the fall of 1891. An examination of the bacteria in 

 a hanging drop preparation showed them to be universally 

 actively motile. They were virulent. 



The number of flagella on the different germs, as observed 

 in the stained preparations, was variable. The most usual 

 number was from two to five. A few germs have been found 

 upon which nine filaments could be counted, but it is the ex- 

 ception to find more than eight. Frequently the filaments are 

 bent upon themselves in such a way that it is very difficult to 

 determine the exact number, especially when it is large. In 



