FORMS OF BACTERIA 9 



which encloses the rods has been supplied by means of a contribution 

 from each of the rods constituting the thread. 



PIG. 17. Crenothrix polyspora. (After Zopf.) 



3. Crenothrix. The threads constituting this genus are similar to 

 those of Cladothrix, but differ in that multiplication of the enclosed 

 rods takes place in all directions, so that a cluster and not a row of 

 cells is formed inside the membrane, as represented in Fig. 17. 



4. Phragmidiothrix. The appearance of this complicated form is 

 sufficiently indicated by Fig. 18. 



