678 



Journal of Agricultural Research 



Vol. VI, No. 18 



spore-forming bacilli (B. malabarensis, B. danicus, and B. oxalaticus). 

 However, figure 1 shows clearly how just this type D, which has hereto- 



FlG. 1. — Life cycle of Bacillus azoiobacter. The broken straight lines divide the different types of growth 

 indicated by the letters A to M . The Greek letters a to X refer to subdivisions. The single- and double- 

 pointed arrows indicate the development of one form from another. The four circles confine, in every 

 case, all those forms which represent together a rather constant mode of life and which have been usually 

 considered as bases for establishing separate species. 



fore so successfully dodged all bacteriologists, represents practically the 

 key to a correct understanding of the whole problem. There are some 



