TEXT-BOOK OF BACTERIOLOGY. 9 



Thus the existence of these extremely fine processes was indis- 

 putably proved, and we naturally regarded their presence as ex- 

 tremely probable also in other moving* micro-organisms in which 

 no such processes had hitherto been discovered. 



This supposition has been fully confirmed since Loffler has suc- 

 ceeded, by means of a peculiar coloring process (the particulars of 

 which will hereafter be described), in showing the existence of the 

 long-sought-for flagella in a large number of important species of 

 bacteria, including some pathogenic ones, as for instance the chol- 

 era bacillus. 



The same experiments revealed some other facts previously un- 

 known. For example, the thick, clumsy-looking, screw-like bacteria 

 which often occur in stagnant water, known as Spirillum undula, 

 possess at each end not merely one flagellum, but a whole bundle 

 of the finest threads, all curved in the same manner. 



In the spirilla of decaying blood the same thing may be ob- 

 served, while in the cholera bacillus we see a micro-organism 

 which, in contrast to most of the others, presents at one end only a 

 flagellum with wave -like curves. The bacilli in this case have, at 

 either pole, a single cilium, rolled up like a whip-lash or a pig's tail, 

 which illustrates a very singular fact made known by R. Pfeiffer. 

 He discovered, with the aid of Loffler's staining method, that the 

 flagella of typhus and some other bacilli do not proceed from the 

 end, but from the side of the micro-organism, and always in a con- 

 siderable number, so that such a bacillus has a peculiar appearance, 

 reminding one, with its long projections, of a centipede or a spider. 



Among the globular bacteria, too, Ali-Cohen and Mendoza have 

 recently found two motile species, and Loflfler has been able to 

 prove the existence of flagella in the Micrococcus agilis of the first- 

 named investigator. In a preparation of this bacterium we may 

 see, with a little care, that the small globular cells which generally 

 cohere in crowded heaps and packets do really show a perceptible 

 locomotion. 



These observations, it is true, give us as yet but isolated facts. 

 The possibility that we may still find more motile representa- 

 tives of the micrococci must of course be granted; yet, on the other 

 hand, it must be noted as a striking fact that we find no traces of 

 locomotion in any of the more common and important species. 



The trembling and wavering which can often be perceived in ex- 

 amining unstained preparations of micrococci is purely molecular. 

 It is the Brownian movement. A somewhat longer observation 

 suffices to convince us that what we see is a mere motion at a place, 

 and not motion from a place. 



