BACTERIA. 47 



ends frequently have very long chains, while those with rounded ends 

 have short chains or occur singly. The same kind of arrangement is 

 maintained among the spirilla. 





a 



FlG. 27. Division forms of bacilli, a, single; b, pairs; c. in threads 



(After Novy.) 



ZOOGLGEA. Some of the bacteria secrete a mucilaginous substance 

 which causes the cohesion of the cells frequently in considerable number. 

 This aggregate of cells may assume some characteristic appearance and a 

 great many attempts have been made by systematists to make use of this 



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Kit- 



FIG. 28. Threads of Bact. anthracis. (After Migula.) 



in the different cases of fission. These zooglceic masses usually assume 

 the forms of pellicles, but their value as diagnostic features is not great. 

 The formation of zooglcea is very frequently only a stage in the life history 

 of an organism. 



