GROUP I. THALLOPHYTA : FUNGI : SCHIZOMYCETES. 



281 



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

 and Spirochsete-forms (Fig. 196, d) ; or straight free filaments, the 

 Bacillus-form ; or straight fila- 

 ments attached by one end, the 

 Leptothrix-f orm ; or the individuals 

 may form cubical masses, as in Sar- 

 cina Ventriculi. Some forms (e.g. 

 Bacterium, Spirochsete, 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 unicellular, is the zoogloea-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 zoogloea- stage is 

 that known as Leuconostoc mesenterioides, which consists of wavy 



FIG. 196. Different forms of Schizo- 

 mycetes : a Microcoecus ; b Bacterium ; 

 c Bacillus with spores ; d Spirillum 

 (diag.: x600). 



111S 



FIG. 197. Bacillus subtilis. A zooglcea-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 Cyanophyceee (p. 231). 



