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MANUAL OF POISONOUS PLANTS 



plication, as before stated, is by simple fission or cell division. Growth takes 

 place very rapidly in many forms, some being capable of growing to their full 

 size and dividing to form two individuals in twenty minutes to half an hour. 

 Under favorable conditions, this rapidity of multiplication explains the import- 

 ance of the results obtained, and the products formed from such small plants. 

 Some forms are capable of moving or swimming about by means of whips or 

 fiagella placed on all sides or simply at the ends. Other forms move by a 

 sinuous or snake-like bending of the body. Many forms are incapable of motion. 

 Spores are formed by many species ; they are called endospores when formed 

 singly within the bacterial cell, and arthrospores when formed by increase in 

 size of the cells of the filament or part of a filament and its splitting into a 



Fig. 21. The root tubercle organism (Rhizobium leguminosarum). 1. General view 

 of root showing tubercles. 7. Root hair and strand with enlargements at a and e. 25. 

 Cross-section of root at b bacterial tissue. 30. Cells of clover plant filled with the organism 

 nucleus at n. 26. Rod and y shaped organisms from 30 more enlarged. 31. Single cell 

 containing bacterioids. After Frank. 



