THE LEUCO-THIOBACTERIA 133 



ciliuni is invariably behind, and about I2ya in length. The cell 

 moves very slowly, covering about 6oo/x per minute, and the 

 movement consists of a slow forward rotation about the 

 longitudinal axis. The cell contains two, sometimes three, 

 highly refractive drops of calcium carbonate. Multiplication 

 is by simple fission, the cell becoming more and more con- 

 stricted in the middle until separation takes place. The 

 daughter cells remain pear-shaped for some time after separa- 

 tion (Fig 236^). 



PsEUDOMONAS HYALINA . This species differs from the pre- 

 ceding ill being only 4 — 6/x long and 2 — 2'5/x broad. Gicklhorn 

 considered them to be distinct species from his failure to find 

 intermediate forms. The organisms P. hipunctatus and 

 P. hyalina, members of the thionic acid bacteria, are further 

 treated in Chap. XII. 



