484 



On the Life-History of Spirillum. 



[June 20, 



between the active and resting states, and ultimately lengthen out into 

 a small filament, which loses its definite twist and may freely bend or 

 straighten. This thread grows into a much larger and longer motion- 

 less filament, in which spores appear. These rapidly divide and 

 acquire a bright brown colour, the filament reassuming the motile 

 condition, and sooner or later breaking up. The freed spores encyst 

 and divide, forming capsules, which after a period of quiescence them- 

 selves become motile, the sporules contained in them escape and germi- 

 nate into " commas," which become Vibrio-like, and soon grow into 

 the common motile Spirillum. 



The resemblance of all this to the life-history of Bacterium termo 

 and Bacillus described in the preceding paper is at once apparent. 

 Not only is there the same alternation of a resting with a motile 

 phase, bat there is a lengthening into filaments the protoplasm of 

 which condenses into spores which divide and germinate. Moreover, 

 there are also moving filaments, and finely granular spheres, while 

 the resemblance to B. rubescens is even more striking. That the 

 deeply coloured spherules, figured by Lankester in the filaments and 

 capsules, and described as " loculi," as well as the so called "sulphur- 

 granules " of Cohn,* correspond to our " spores " is extremely probable, 

 although their germination has not yet been observed. 



EXPLANATION OF PLATES. 

 Plate 11. 



The left half of the drawing represents a portion of a large glcea film of 

 resting Spirillum, containing also (1) a motile mycelium of spore-bearing 

 filaments, (2) many spore capsules, grouped and isolated. On the left are 

 free active Spirilla, which have disengaged themselves from the film ; at • 

 (a) they are crowded, showing a distinct brown colour ; at (b), where I he 

 liquid is drying up, is shown the intertwisting of the longer spirals, which 

 not unfrequently occur. Many motile spore capsules are shown, also a 

 filament breaking up. 



Spirilla beginning to lengthen into filaments. 

 Young filaments still freely motile. 

 (a.) Similar young motile filaments. 

 (b.) More fully developed filaments, no longer motile, 

 (e.) A filament, of which the protoplasm is condensing into round faintly- 

 coloured spores. 

 Two successive drawings of a ripe motile filament. 



Plate 12. 



Part of a mature motile filament, showing the irregular size and arrange- 

 ment of the budding and dividing spores, also empty spaces whence spores 

 have been dropped (a) . 



Successive sketches of a filament breaking up. (a.) Spaces occupied by 

 spores. 



Figure 1. 



Figure 2. 

 Figure 3. 

 Figure 4. 



Figure 5. 

 Figure 6. 



Figure 7. 



* " Beitrage zur Biol. d. Pfl.," 3, 1875. 



