The Character of the Flagclla 353 



locomotion. This is suggested by watching the clumps of 

 bacteria in a hanging-drop preparation. The germs at the 

 edge of these masses, when about to separate themselves from 

 the others, exhibit first a trembling motion, then a jerking, 

 reeling and pitching movement, until finally thej' are free* 

 and move across the field. 



Furthermore, in the examination of a hanging drop prepa- 

 ration made from a bouillon culture the bacteria are observed 

 to move much closer to each other than the length of their 

 flagella, and it seems highly probable that detachment or 

 breaking of the appendages is produced during these volun- 

 tary movements, by their contact and possible entanglement 

 with each other. Free flagella have been found to be numer- 

 ous in stained preparations made from liquid cultures. For 

 the ultimate settlement of these questions a method must be 

 devised by which the motile appendages can be observed on 

 the living and moving germs. At present we are forced to be 

 content with the study of the appearances that are presented 

 in stained specimens, presuming that as the conditions of 

 preparation are the same the characters that are revealed will 

 be correspondingly similar in the different species. 



The length of the flagella as seen in stained preparations 

 varies to a marked degree. The longest I have measured was 

 18 /x or about nine times the length of the body of the 

 bacillus (hog cholera). 



The diameter of the flagella varies in different preparations 

 and frequently in the same specimens, to a marked degree. 

 In a deeply stained preparation they are occasionally 0.4 /x 

 in diameter, or about one-third of the diameter of the body of 

 the germ. More commonly they are about o. 2 /x in diameter, 

 or about one-sixth the thickness of the organism. Again they 

 may appear as extremely delicate lines, so fine that it is with 

 difficulty that they can be seen at all. Usually, however, 

 they are about 0.2 /a in diameter. The unexpected appear- 

 ance of these variations has thus far baffled an explanation, 



* It is an observable fact that the character of the movement of the 

 individual germs is somewhat varied. This may be due to the loss of 

 certain of their motile appendages. 



