GROUP I. THALLOPHTTA : FUNGI : SCHIZOMYCKTES. 



281 



c== v 







Bacterium- form (Fig. 196, 6); or spirally- wound, the Spirillum- 

 and Spirocheete-forms (Pig. 196, d) ; or straight free filaments, the 

 Bacillus-form ; or straight fila- 

 ments attached by one end, the 

 Leptothrix-form ; or the individuals 

 may form cubical masses, as in Sar- 

 cina Ventriculi. Some forms {e.g. 

 Bacterium, Spirochcete, and some 

 Coccus-forms) are capable of loco- 

 motion; but it is uncertain how 

 the movement is executed. These 

 forms are provided with one (Coc- 

 cus-form) or more (one or more at 

 each end in Bacterium- and Spiro- 

 chsete-forms) delicate filaments, 



which are regarded by some as vibratile protoplasmic cilia, by 

 means of which movement is effected, whereas others consider 

 them to be simply prolongations of the cell-wall. 



A remarkable phase, common to the life-history of nearly all 

 forms, more especially the nnicellular, is the zooglcea-stage. It 

 consists of great numbers of cells held together by bulky mucilage, 

 to form either a membrane (e.g. the scum on putrifying liquids) 

 or masses of the most various form. A striking zooglcea-stage is 

 that known as Leuconostoc mesenterioides^ which consists of wavy 



Fi&. 190. Different forms of Schizo- 

 mycetes : a Micrococcus ; f> Bacterium ; 

 c Bacillus with spores; d Spirillum 

 (diag.: x600J. 



FIG. 197. Bacillus subtilis. A zoogloea-stage ; B motile stage ; C zoogloea-stage, with 

 spore-formation. (After Strasburger : x 800.) 



chains of cocci imbedded in a mass of mucilage, the whole re- 

 sembling the structure of Nostoc in the Cyanophyceae (p. 231). 



