April 16, 1920] 



SCIENCE 



391 



sity, has been selected by the trustees' com- 

 mittee on general administration to be acting 

 president of the university until a permanent 

 successor to Dr. Schurman is appointed. 



The professorship of electrical engineering 

 at Lafayette College, made vacant by the 

 resignation of Professor Rood, vs^ho left 

 Lafayette to go to the University of Illinois, 

 has been filled by the appointment of Pro- 

 fessor Morland King, of Union College, as 

 associate professor of electrical engineering. 



Dr. Walter K. Pishee, of the department 

 of zoology at Stanford University, has been 

 promoted to an associate professorship. 



Dr. Max Mailhodse has resigned as clinical 

 professor of neurology in the Tale School of 

 Medicine, his resignation to take effect at 

 the close of the present college year. 



DISCUSSION AND CORRESPONDENCE 



A SUGGESTION AS TO THE FLAGELLATION OF 



THE ORGANISMS CAUSING LEGUME 



NODULES 



A VERY interesting note by Hansen on the 

 flagellation of the legume nodule organisms 

 (Ehizobium) appeared recently in this jour- 

 nal.^ There has been a dispute for some time 

 as to whether these bacteria have one or 

 several flagella. Burrill and Hansen not long 

 ago- claimed that they are monotrichic organ- 

 isms, whereas various other investigators, in- 

 cluding the present writers,' have observed 

 peritrichic flagella. Hansen now says that he, 

 too, has found peritrichic flagella on cultures 

 obtained from clover, vetch and alfalfa, and 

 calls attention to the fact that his earlier 

 studies had been on organisms from cowpea 

 and soy bean. Hence he suggests that there 

 may be two different groups, one peritrichic 

 and the other monotrichic. It is, indeed, gen- 



1 Hansen, Boy, ' ' Note on the flagellation of the 

 nodule organisms of the Leguminosse, ' ' Sci., N. S., 

 50: 568-569, 1919. 



2 Burrill, T. J., and Hansen, E., "Is symbiosis 

 possible between legume bacteria and non-legume 

 plants?" 111. Agr. Exp. Sta., Bui. 202, 1917. 



3 Breed, E. S., Conn, H. J., and Baker, J. C, 

 "Comments on the evolution and classification of 

 bacteria, ' ' Jour. Bad., 3, 445^59, 1918. 



erally recognized that the organisms of cowpea 

 and soy bean differ from the other varieties of 

 Bhizoiium in certain cultural features, pri- 

 marily in respect to vigor of growth. 



Hansen's suggestion is very interesting, but 

 does not explain all the facts that have been 

 observed. Wilson* has found peritrichic fla- 

 gella on cultures of the soy bean organism. 

 To be sure, as insisted by Hansen, Wilson has 

 not published any photomicrographs; but the 

 statement he naakes is definite and no one 

 need question it. We have seen one of Wilson's 

 microscopic preparations (soy bean organism) 

 and also one of Hansen's (cowpea organism) ; 

 and find four or five flagella on some of the 

 bacteria in Wilson's preparations, but only 

 one each on those in Hansen's. 



Upon enquiry we find that Wilson's cul- 

 tures were sometimes as old as 28 days at the 

 time of staining; while it appears from Bur- 

 rill and Hansen's paper that their prepara- 

 tions were only a few days old. In this con- 

 nection it is an interesting fact that a certain 

 organism (belonging to a different group) 

 studied in this laboratory was found to have 

 a single polar flagellum when a few hours 

 old, but two or three polar flagella when a 

 day or more old. This naturally raises the 

 question whether the cowpea and soy bean or- 

 ganisms may not be monotrichic in young 

 cultures and peritrichic when they are older. 

 This suggestion is further borne out by the 

 fact that Hansen found (as shown by state- 

 ments in his text and by his photomicro- 

 graphs) the single flagellum to be attached at 

 the corner or even at the side more often than 

 exactly at the pole. This is just what would 

 be expected if it were a matter of chance 

 which one of the peritrichic flagella developed 

 first in a young culture. 



Ever since the appearance of Burrill and 

 Hansen's paper we have wanted to investigate 

 the truth of the matter. As we have not had 

 the chance to do so, we take this occasion to 

 put the idea in print that any one else inter- 



* Wilson, J. K., ' ' Physiological studies of Bacillus 

 radioioola of soybean {Soja Max., Piper) and of 

 factors influencing nodule production," Cornell 

 Agr. E±p. Sta., Bui. 386, 1917. 



