302 APPENDIX. 



to this nomenclature, which appears to be adopted by 

 histologists, so as not to overload the synonymy of 

 microbes, which is already somewhat encumbered. It is 

 probable, moreover, that this assimilation is correct, 

 and that most bacilli pass through a phase in which they 

 are short and mobile, before becoming elongated and 

 stationary. On the other hand, certain types of the old 

 genus Bacterium for instance, the bacteria in the form of 

 an 8 should rather be assigned to the genus Micrococcus, 

 or to the new genus Diplococcus. 



With respect to the genus Vibrio, it seems to have 

 been originally only a somewhat heterogeneous collection, 

 comprising both the chains and chaplets of micrococci or of 

 short bacteria, and the strictly unicellular organisms which 

 might be assigned to the genus Spirillum. Klein, how- 

 ever, reserves this genus for Vibrio rugula and V. Serpens. 



The genus Hicrococcus (Hallier) is also termed by> 

 Cohn, Spherobacterium, and these two names are now 

 given to the only unicellular microbes which are round 

 or oval, stationary, and consequently devoid of eilium or 

 flagellum, the organ of propulsion. 



These micrococci may be in the form of chains or 

 chaplets (torula), dumb-bells (Klein), the figure 8 (Diplo- 

 coccus, Billroth), groups of four, and zoogloea3 or in masses 

 of greater numbers. 



The genus Bacterium (Microbacterium, Cohn) differs 

 from the foregoing, as Klein states, chiefly in the oval or 

 cylindrical form of its cells, and still more by the presence 

 of a eilium or flagellum at one extremity, which gives a 

 spontaneous movement. They may thus assume the form 

 ot a sponge-cake and of a dumb-bell when they divide in 

 two, and may also form short chains or zoogloeae. As we 

 have already said, most of these organisms are assigned 



