1878.] 



Bacterium termo and Micrococcus. 



479 



the peach-coloured granular disks figured by Lankester from old culti- 

 vations of Bacterium rubescens, in which " the nourishment had dwin- 

 dled to its very smallest limit." 



In the zoogloea all the Bacilli were quiescent, and it is important to 

 observe that in none of them was there any appearance of division ; 

 but around the edge (Series I, ti) some were in active motion, 

 whether entering or leaving the motile stage I do not know. The 

 close resemblance of these masses, both in form and in time of 

 appearance to the " macroplasts " of Lankester,* led me to watch 

 their development. First, the spore divided into four sporules quite 

 as in Bacillus OMthracis,\ but these sporules again divided forming a 

 granular mass (Series IV, d, e), division and growth going on simul- 

 taneously till a large very finely granular sphere was produced. 

 (Series IV, g.) 



When one of the large spheres was broken up, round particles 

 (Series IY, h) spread far and wide over the field. These particles, 

 when placed in a fresh drop of sea water enlarged (Series IV, i) and 

 germinated into rods. (Series IV, j.) 



If then a single minute spore is thus capable of producing innumer- 

 able still more minute germs, and if these, as all experiment tends to 

 show, resist desiccation at ordinary temperatures, Professor Huxley's 

 dictum may unhesitatingly be repeated and endorsed, that, consider- 

 ing the lightness of Bacterium germs, and the wide diffusion of the 

 organisms which produce them, it is impossible to conceive that they 

 should not be suspended in the atmosphere in myriads. 



Morphological Considerations. 



Various investigators, notably Huxley and Lankester, have long 

 ago asserted the Protean nature of Bacteria, and the accompanying- 

 plate (exclusively compiled from actual observation), is an attempt to 

 summarise and define what we at present know of the phases 

 through which three of these forms, Bacillus, Bacterium, and Micro- 

 coccus may pass. Such a diagrammatic representation may be the 

 more useful, seeing that at present our knowledge is scattered through 

 many papers. 



Series I represents the most common phases through which 

 Bacillus may pass. The spore germinates into a rod, this divides, the 

 portions, if at rest, either falling apart or forming a jointed filament 

 (/). The motile stage may be assumed, during which division also goes 

 on (q), zigzag forms being produced which have often been mistaken for 

 Vibriones. While division is going on, the development of the cilia is 

 often beautifully seen with a high immersion. First, the cellulose 



* " Quart. Journ. Micro. Science," vol. xvii, New Series, p. 27, Plate III. 

 f Loc. cit. 



