STUDIES ON GROWTH CYCLE OF AZOTOBACTER 333 



9. Heat-resistant endospores are not produced. 



10. Involution forms varying much in size and shape occur 

 commonly in cultures more than fourteen days old, in Ashby's 

 solution or on Ashby's agar at 25°C. They are particularly 

 numerous when cultures are grown at 37°C. 



11. Some involution forms appear to multiply to a very limited 

 extent by a budding process. 



