552 Journal of Agricultural Research vol. xx, no. 7 



not most of the commonly used so-called species names of bacteria are 

 no species names at all, but merely denominations more or less correctly 

 applied to organisms about whose complete life history and, accord- 

 ingly, about whose true systematic value and position comparatively 

 little is known at present. 



It is by no means impossible that future systematic investigations may 

 demonstrate the peritrichic and the cephalotrichic nodule bacteria to 

 be relatively constant types of growth of one species. There are a few 

 reports in the literature indicating that occasionally cross inoculations 

 have been obtained, which might support this hypothesis. While O. 

 Kirchner never found nodules on soybeans grown in Germany and there- 

 fore thought his Rhizobacterium japonicum to be the active agent in the 

 Far East, F.. Cohn said in a note appended to Kirchner's report that 

 soybeans grown for the first time in his experimental garden in Breslau 

 did produce nodules, though these were not of the normal type and con- 

 tained only a few rodlike bacteria. Kellerman reported upon a case 

 where a culture originally isolated from alfalfa was found to be infective 

 on alfalfa and lupine as well as on soja when tested by Leonard after 

 six years' cultivation on artificial substrates. It may be mentioned also 

 in this respect that cross inoculations between navy bean and cowpea 

 seem to be equally possible, under circumstances, however, which need 

 further elucidation. 



But just as negative results in cross inoculation experiments can not 

 be accepted as sufficient basis for establishing different species, so also 

 such rather exceptional positive results can not be used as valid support 

 of the hypothesis that monotrichic and peritrichic nodule bacteria are 

 only two types of growth of the same species. First of all, it would have 

 to be ascertained whether in such cases the peritrichic organism has 

 really changed into the monotrichic one, or vice versa. The possibility 

 remains, of course, that occasionally the one type of organisms may 

 invade a host plant whose nodules are normally caused by the other 

 type of bacteria. 



Changes in flagellation from peritrichic to cephalotrichic have been 

 observed, according to Lehmann and Neumann (n, p. 256, 357, 371), 

 with Bacillus coli and B. alcaligenes. Both species are related to B. ra- 

 diobacter and B. radicicola, and under this aspect an analogous change 

 should not be rejected prematurely as a priori improbable. 



At the end of the introduction three statements have been quoted from 

 the more recent literature which one might be inclined to accept as con- 

 firmative evidence in this direction. However, on account of the follow- 

 ing reasons we do not feel justified in advocating such an interpretation. 



J. K. Wilson says that in his preparations of soybean organism — 



The flagella were peritrichous, the highest number found being four. 



As no photomicrographs had been made, Dr. Wilson was kind enough 

 to furnish, on request of the senior author, one of his slides for examina- 



