22 MICROBIOLOGY 



tions made in a drop of serum. 1 It is quite generally be- 

 lieved that there is a thin capsular substance surrounding 

 all bacteria and that it represents a swelling of the ectoplas- 

 mic zone of the organism. 



Flagella. Flagella are fine hair-like appendages vary- 

 ing in length from a few to many microns, radiating from 

 the bodies of the motile bacteria. They are the organs of 

 locomotion or motility. They are distributed over the entire 

 body or they may occur singly or as tufts at one or both ends 

 of the organism. The polar flagella are said to appear on 

 the bacteria shortly before division. Like the capsules, they 

 require a special stain. They were observed on some of the 

 larger saprophytic bacteria in fresh preparations by Dai- 

 linger and Drysdale. 2 



The flagella seem to come either from the cell wall or 

 ectoplasma or the capsular like substance. In cultures of 

 bacteria possessing many flagella there frequently occur 

 bundles of more or less twisted, detached flagella. It has 

 been stated that certain bacteria may lose their power of 

 producing flagella after a number of generations. 3 This has 

 not been the observation of the writer. 



The flagella were thought by Tavel 4 and Luksch 5 to be 

 of value in differentiating closely related species. Messea * 



1 Hiss has somewhat recently (Journal of Experimental Medi- 

 cine, Vol. VII (1905) p. 223) called attention to this method of dem- 

 onstrating capsules although it has long been followed in certain 

 laboratories. 



2 Dallinger and Drysdale, Monthly Microscopical Journal, Lon- 

 don, Vol. XIV (1875) p. 175. 



Also, Journal of the Royal Microscopical Society, Vol. I, p. 175. 



3 As possibly bearing on this point, the writer isolated an or- 

 ganism from a pig which possessed all the physiologic and patho- 

 genic properties of Bacillus suipestifer but it did not possess flagella 

 and was not motile. Dr. Theobald Smith has also published a de- 

 scription of a like organism. 



4 Tavel, La semaine Med., 1892, p. 52. 



5 Luksch, Centralb. f. Bakt, Vol. XII (1892) p. 427. 



6 Messea, Rivista d'igiene e sanita public, No. 14 (1889) p. 513. 



