The Morphology of Root Tubercles of Leguminosae

Abstract

The object of this research was to give a more detailed account of the anatomical structure of root tubercles, thus adding perhaps somewhat toward clearing up some of the difficulties in the comparatively little known field of teratology. It is true much labor has been expended in the endeavor to get a correct understanding of symbiosis and the relation of Rhizobia to certain plants. The life history and :morphology of the root bacteria have received most of the attention while the tubercles themselves have been almost entirely forgotten. Frank, who has done much in this line of research offers but little concerning tubercle morphology. Nearly all of his attention is directed toward the Bakteroiden. The same is true of Beyerinck, Brunchorst, AWaronin and the others. Some of the pupils of Frank have also made noteworthy researches concerning Rhizobia. Recently Frank and Moeller2 have engaged in a controversy with regard to the Dimorphismus der Wurzelknbllchen der Erbse. Frank has also described the lenticular structure of root tubercles. Beyond this, little of importance seems to have been done with root tubercle mnorphology. In my own researches, mature tubercles were taken from various Leguminosm toward the close of the vegetative period, since at that time tissues have acquired their most marked morphological characteristics. The earlier stages of development were studied at various periods of the season. The final summing up was not completed until late in the year. (Dec., 1892.) The tubercles are in themselves abnormal growths produced by the local irritation of certain organisms, the Rhizobia; and