124 SYSTEMATIC BOTANY. 



spores burst open, the protoplasm of each escapes as a 

 swarm-spore with one cilium, and undergoes fission. Coa- 

 lescence of a number of these takes place in a few days 

 to form the plasmodium. 



157, The Bacteria (Schieomycetes) are Protophyta, des- 

 titute of chlorophyll. They are exceedingly small and 

 simple organisms (Fig. 234), present in fermenting and 

 putrefying matter, and sometimes in the blood of diseased 

 animals. They occur isolated, or in cell-families, and 

 multiply exclusively by transverse fission ; most of them 

 have a motile and a motionless stage. The unicellular 



/ ,- «,,, „ Bacteria sometimes form a 



'"iW All 



- ' /W. w i \ "k. jelly-like mass or colony, 



probably in consequence of 

 the swelling up of their cell- 

 walls, and this is called the 

 eooglea stage (Fig. 234, Bd). 

 The common agent of putre- 

 faction is Bacterium termo, 

 which consists of very small cylindrical cells. B. oerugi- 

 noswn is found in blue-green pus. The genus Micrococcus, 

 consists of spherical cells (Fig. 234, Micr). M. prodig- 

 ioms causes the blood-like patches on bread, paste, etc. 

 M. diptherieus causes, or at least accompanies, diptheria. 

 There are two genera, with filiform cells; BaciUus, with 

 the filament straight (Fig. 234, Bd) ; and Vibrio, with the 

 filament curved or undulated (Fig. 234, Ft6). B. subtUis 

 is the butyric ferment, and B. anthracis causes the anthrax 

 or splenic fever. The genus Spirillum (Fig. 234, spZ) has 

 spirally twisted cells. S. volutans is a comparatively large 

 species with a flagellum or cilium at each end. 



Fig. 234, Bacteria; Micr^ Micrococcus prodigicsus : Bct^ Bacterium iermo; 

 Bel, Bacillus ulna; Vib, Vibrio r,ug;ula; Spl, Spirillum volutans; Spck, Spira^ 

 cheeteplicatilis. 



