244 IVAN V. SHUNK 



different results obtained by Wilson (1917) who found peritrichic 

 flagella on the soy bean organism, and Hansen (1919) who found 

 the single flagella on organisms from the same host, are due to 

 the age of the cultures at time of staining. From inquiry Conn 

 learned that Wilson's cultures were sometimes as old as twenty- 

 eight days, whereas Hansen used two to three day old cuhures. 

 Conn suggests therefore, that the organism may be of the single 

 flagellate type when two or three days old and becomes peritrichic 

 when older. However, Wilson's paper (1917) states that the 

 flagella were stained from one to seven day old cultures so the 

 peritrichic flagella must have been present in seven days or less, 

 and he furthermore makes no reference to finding single flagella 

 in the younger cultures. 



While the writer has been unable to stain flagella on the soy 

 bean organism from very old cultures, yet he has found that up 

 to ten days old the cultures still show the single flagellate type, 

 with no indication that they will ever be anything else. 



Wilson demonstrated that his peritrichic organism was able 

 to form nodules on soy beans, and the strain of the single flagel- 

 late soy bean organism used by the writer has also been shown to 

 be able to produce nodules when grown according to the method 

 of Garman and Didlake (1914). This brings the writer to the 

 conclusion that in different sections of the country, there is a 

 different adaptation of nodule bacteria to the soy bean, and that 

 Wilson and Hansen were w^orking with the two different types. 



Although a similar adaptation might be expected in the case 

 of other legume host plants, yet it is interesting to note by 

 referring to the groups of nodule bacteria found by Burrill and 

 Hansen (1917) that if one host plant in a group has single flagella, 

 all other host plants of that group which were investigated gave 

 single flagella, and similar results were obtained in those groups 

 having peritrichic flagella. 



SUMMARY 



1. The flagellation of the organisms from nodules of 41 species 

 of leguminous plants has been studied. 



2. Two distinct types of flagellation have been found, the single 

 flagellate type and the peritrichic. 



