CYTOLOGY 



LIFE-HISTORY 



BACTERIA 



Miss PInlhs E Pease) 



Figs, .'ui and .")4- 

 THE LIFE-CYCLE OF CAULOBACTER 

 The life-cycle of the true, stalked caulobacteria provides an example of the alternation 

 of sessile and motile generations, such as is commonly found in other biological groups. In 

 Fig. 53 the entire cycle is seen foreshortened. The stalked cell is producing a flagellate daughter 

 cell. Fig. 54 shows the complete life-cycle. The stalked generation (1) is shown in process of 

 division. In (2) the flagellate daughter cell is shown. In (3) are two flagellate cells in the 

 process of becoming sessile. In the upper example the stalk has already developed, but the 

 flagellum (slightly outhned for clarity) is retained. In the lower example the stalk is in an 

 early stage of development. Electron micrographs, gold-shadowed. Fig. 53 and Fig. 54 (1) 

 X 20,000; Fig. 54 (2), (3) ■ 15,000. 



for reproductive purposes. Chlamydobacteria are aquatic and instead o£ 

 aerial spores produce motile swariner cells, which swim actively by means 

 of flagclla. 



The vegetative cells grow as a long filament, surrounded by a sheath o£ 

 colloidal iron. At the ends of the sheath the cells may be transformed into 

 flagellated swarmers, which swim oft' to found new filamentous colonies. 



