.lull.-. I!IL'1. 



SCIENTIFIC AGRICULTURE 



IfA 



morpliologically as wclj as culturally. It is equally 

 beyond di.spute that these differences are so marked 

 and constant that one mi^ht be inclined to establish 

 the nodnle organism of the cowpea-snybean group as 

 a new .species. On account of its belhavior in the 

 inoculation test 0. Kirchner has considered the soy- 

 bean organism a di.stinot species, which he named in 

 1895 Rhisobacferimn japonicum (10). According to 

 t;hc rules of priority, tfliis species name would have 

 to be given preference, despite t'ne fact that different 

 behavior in the inoculation test generally cannot be 

 accepted as a distingui.shing mark of such quality as 

 to validate the creation of a new species. The generic 

 name Rhizobacterium, iised by Kirchner, is, of course, 

 equally as untenable as the generic name Rhizobium. 

 According to the two most frequently used modes 

 of classifying the bacteria, one might name tjiie 

 ceplhalotrichic non-sporulating rod of the cowpea-soy- 

 bean group Pseudomonas japonica or Bacterium japon- 

 icum, while the name Bacterium or Bacillus radicicola 

 would have to be retained for the peritrichic organ- 

 iSnLs to be found- with clover, alfalfa, sweet clover, 

 vet<ch, pea, ^tc. 



However, we do nut advocate such a procedure. 

 We are firmly of tjbe opinion that much more must 

 be known of the complete life history of a baeteriiun 

 tlhan is obtainable along the standardized lines of 

 customary bacteriological research, before one can 

 safely proceed to establish a genuine species on a 

 truly scientifir- basis. Undoubtedly many if not most 

 of the commonly used so-called species names of bac- 

 teria are no species names at all, but mierely denom- 

 inations more or less correctly applied to organisms 

 about whose complete life histoiy and, accordingly, 

 about whose true systematic value and position com- 

 jiaratively little is known at present. 



It is by no means impassible that future systematic 

 investigations, may demonstrate the peritrichic and 

 the ccp^ialotriehic nodule bacteria to be relatively con- 

 stant types of gro-wi:h of one species. There are a 

 few reports in the literature indicating that occasion- 

 ally cross inoculations have been obtained, which 

 might support this hypothesis. Wliile 0. Kirchner 

 never found nodules on soybeans grown in Germany 

 and tviierefore thought his Rhizohactcrium japonicum 

 to be the active agent in the Far East, F. Cohn said, 

 ill a note appended to Kirchner's report that soybeans 

 grown for the first time in his experimental garden 

 in Rre.slau did produce nodules, though these were not 

 of the normal iyY>e and contained only a few rodlike 

 bacteria. Kellerman reported Tipon 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 aft«r six years' cultivation 

 on artificial substrates. It may be mentioned also 

 in this respect that cross inoculations between navy 

 bean and cow^ea seem to be equally possible, under 

 circumstances, however, whidh need further elucida- 

 tion. 



But .iust as negative results in cross inoculation 

 experiments cannot be accepted as sufficient basis 

 for establishing different species, so also .such rather 

 exceptional positive re.siilt^ cannot be used as valid 

 support, of the hypothesis that monotrichie and peri- 

 trichic nodule bacteria arc only two types of grow^.ii 

 of the same species. First of all, it would have to be 

 a.scertained wHietlier in such cases the peritrichic 

 organi.sm has really changed into the monotrichie one, 

 or vice veiva. The possibility remains, of course. 



t.iuit occasionally the one type of organism may invade 

 a host plant whose nodules are normally caused by 

 the other type of bacteria. 



Changes in flagellation from peritrichic to ceplhalo- 

 trichic have been observed, according to T..elimann 

 and Neumann (11, p. 256, 357, 371), with Bacillun 

 raU and B. alcaUf/e^^es. Both species are relatwl to 

 li. rurh'obacter and B. ra<Ucicola, and under this a.spect 

 an analogous change should not be rejected premature- 

 ly 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 confirmative evi- 

 dence in this direction. However, on account of the 

 following rea.sons we do not feel justified in advo- 

 cating .such an interpretation. 



•T. K. Wilson says that in his preparations of soy- 

 bean organism — 



"The flagella were i)eritrichous, the highest •nnni- 

 ber found being four.'' 



As no photomicrogi-aphs Hiad been made. Dr. Wilson 

 was kind enough to furnish, on request of th^ senior 

 author, one of his slides for examination. The fla- 

 gella visible therein were all very weakly .stained, so 

 that no definite conclusion coiild be dra-ivn. A cul- 

 ture for which we are also indebted tiO Dr. Wilson, 

 behaved in our .hands like all those tested before: 

 practically all cells were distinctly monotrichous. A 

 comparison of Plate 68, A, with the pictures published 

 on Platen IV and V of Bulletin 202, Illinois Agri- 

 cultural Experiment Station ('6). leaves no ddubt 

 about this point. 



In Barthel's ])aper (2, j). 16~) two dravdngs and one 

 photomicrograph are to be found which clearly illus 

 trate the following statement: 



"Bei den Lupinenbakterien sind die Geisseln ziemlich 

 lang, wellio- geformt und an einem Pole l>efestigt. 

 Thre Anzahl variiert von 1 bis 6. Ihre Placierung 

 ist reeht eigentiimlich. 8ie .sitzen niimlich ofters 

 nicht gerade an der Spitze des Zellleibes, sondern 

 sozu.sagen an den "Ecken" und oft etwas von dem 

 Hinterende entfernt. Oft findet man auch cine Geissel 

 an der einen "Hinterecke" und mehrere endere zu- 

 sammen an der anderen. . . 



Bei den Luzernebaktierien waren die Geisseln meist 

 weniger und kiirser, am haufigsten 1 oder, j5eltener 

 3 oder 4, aber auch hier deutlich lophotrich. . ." 



Fred and Davenpoi-t (7'l, on the other ijiand, .saw 

 only one or two cilia with the lupine bacteria, while 

 several strains of alfalfa organisms left no doubt as 

 to their peritrichic flagellation. 



We believe that these conflicting views are in fact 

 not .so irreconcilable as they seem to be. If well-made 

 slides are examined carefully, some cells will always 

 be discovered which clearly show that on account of 

 ti'ie primary swelling and t.iie following shrinking of 

 their capsules, the flagella are often more or le.ss 

 dislocated. Some of tiie cells shown in Plate 68, 

 A-C, exhibit this phase as clearly as it is possible 

 in such reproductions. The flagella of the mono- 

 trichous bacteria of the cowpea-soybean group are to 

 be seen in an exactly polar position only when the 

 cells themselves are lying lengthwise witihin t.iie 'drift', 

 as indicated by the floating flagella. In all other 

 cases dislocations may take place, i-emoving the cilia 

 to the corners oi- even to the side of the cells, where 

 they should not be viewed, however, as remnants of 

 a neritrichic flagellation. 



Oh the other hand, analogoiLs disturbances may cause 



