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APPLIED BACTERIOLOGY 



multiply by division, giving rise to irregularly - shaped 

 zoogloea masses, sometimes of enormous size. When cul- 

 tivated in marsh-water the cocci grow into rods, which by 

 continuous division form filaments which radiate out in 

 all directions from the zoogloea. When this growth has 

 attained a certain age, a sheath is produced which contains 

 ferric hydrate. By a continual process of division which 

 takes place within the sheath, such a pressure is exerted 

 against its top end that it is forced open, and thus the 

 rods and cocci escape. Sometimes the cocci and rods 



Fig. 29.— Ckenotheix Kuhniana. 



develop within the sheath into rods and threads, and push 

 their way through the walls of the sheath, giving rise to a 

 paint-brush appearance. 



(&) Beggiatoa. — The Beggiatoa are distinguished by the 

 presence of grains of sulphur in the cells, which are seen 

 as highly refracting granules. The Beggiatoa are widely 

 distributed, and are found both in fresh and salt water con- 

 taining decomposing vegetable and animal matter. In the 

 waters of sulphur springs they are especially abundant, 

 and accumulate upon the muddy bottom, or upon the 

 organic matter undergoing decomposition, as a white, gray, 



