Chromosome Numbers in Root Nodules and Root Tips of Certain Leguminosae

Abstract

1. Infected cells of root nodules of thirty-one diploid species belonging to Lathyrus, Medicago, Melilotus, Pisum, Trifolium, and Vicia contain in each case the tetraploid number of chromosomes.2. Uninfected cells in the nodular cortex possess the diploid number characteristic of the particular species. 3. The chromosome number in infected nodular cells in diploid and autotetraploid strains of Melilotus alba is in each case twice that characteristic of uninfected somatic cells of the same plant. 4. The chromosome number in infected cells of the nodules from diploid, triploid, tetraploid, and octoploid species and races of Medicago is in each case double that in root tip cells. 5. Infected nodular cells from plants of a natural polyploid series in Trifolium possess in each case twice the somatic number of chromosomes. 6. Inhibition of the fixation of free nitrogen by such conditions as infection with an ineffective strain of Rhizobium, the presence of combined nitrogen in the nutrient, or the presence of h...