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Settled Facts. 
1. That certain fungi are symbiotic in and on roots of certain 
plants. 
2. Some of these fungi are purely parasitic, while others have 
the power of assimilating for the use of the plant free nitrogen 
of the air. 
3. Plants can exist without these fungi, but as a rule thrive 
better with them. 
4. At the close of vegetation, and also on other special occa- 
sions, the plant reabsorbs the protoplasm of the fungi. 
5. The Infektionsfiiden are not hyphe of which the Baktet- 
eoiden are the spores or gemmules. 
Probable Facts. 
1. That there are at least several species of Rhizobium. 
2. That the Infektionsfaden have nothing to do with the 
Rhizobia under consideration. 
3. That the Rkizobia belong to the Schizomycetes. 
4. That Rhizobium mutabile has no spores. 
5. That the Infektionsfaden are true hyphal fungi allied to 
Schinzia Alni. 
Lmprobabilities. 
I. That the Infektionsfiden are plasmodia. 
2. That the Bakteroiden are not living organisms. 
3. That the plant exerts any attractive influence upon the 
Rhizobia. 
4. That some plants cannot exist without the symbiotie 
fungus. 
The researches of which this paper is a partial record, be 
undertaken in 1890 and 1891, in the Laboratories of Botamy, * 
_ the University of Minnesota, in Minneapolis. 
BIBLIOGRAPHY. 
Benecke, F. (Botanisches Centraiblatt, 1887, No. 2). 
Beyerinck, M. W. (Botanische Zeitung, 1890, No. 52): 
sg “ (Botanisches Centralblatt, 1891, No. 8). 
