236 The Botanical Gazette, [June, 
min, °° Pichi,*® A. Koch,*? and Laurent®® that a membrane — 
does exist. 
Short communications by Delpino®®. and Mattei®® about | 
this time support the view that the tubercles are caused by 
bacteria. 
In 1890°! Frank appears with still another contribution. 
While he does not wholly return to his earlier convictions he 
retraces his steps far enough to once more champion the 
causal relation of some soil organism. This time he believes 
the organism to be micrococcoid and names it Rhizobium legu- 
minosarum. He still recognizes the two form elements in 
the tubercles, the hypha-like strands and the bacteroids 
The former he believes to be a homogeneous mixture of the 
cell protoplasm of the two symbionts, in which nothing 
is visible indicative of the nature of the Rhizobium ot the 
protoplasm of the leguminous plant. This mixture he terms 
mycoplasm. Upon treatment with certain reagents the por- 
tion of the mycoplasni belonging to the host plant dissolves — 
and sets the micrococci free. Frank also obtained his Riise 
dium in artificial culture and produced the tubercles by inoc- 
ulation with the same. The bacteroids he regarded as frag- 
ments of the mycoplasm, while in a more recent communica: 
nt he says they are hypertrophied forms of the Riis 
zum. 
the bacteroids and fungus strands, believing with Ward a8 
the earlier tenets of Frank that the bacteroids are budde 
i. Agr. Franc. et etrang. 1888. p. 96. : tti della 
*SAlcune osservazioni sui tubercoli radicali delle Leguminose. 4 
ce naturali. 1888. : 
“oad ara thee der Faden in den Wurzelkndllchen der Leguminos 
n. d. l'Institut Pasteur. v. (1891). 105-139 : 
*°Osservazioni sopra batteriocecidii e la sorgente |’ azote in una piante 
officinalis. Malpig. 1. fase. 9-10. (1889). Cited by pie Vv i 
21 puerta sul’ origine della Vicia faba. Bologna. 1887. Cited by 
ni Ueber die Pilzsymbiose der Legumin n. Berlin, 1890. 
Beric deutsch. bot. Gesellsch. 1x. (1891). 244-253. Rend & x. 
Spo des nodosités des Légumineuses. Compt. fie 
> 1890. pp. 754-756. ans 
role sur les nodosités radicales. Ann. d. I' Inst. Pastevt 
739. 
te d. 
‘ ®°8Sur le microbe 
