1955 Volume 68 Issue 808 Pages 267-273
1. If the seeds and growing points of the seedlings of theA. crispa and the A. punctata are treated with each solution of high concentration of streptomycin, aureomycin, chloromycetin and terramycin, knobs are formed on various growing points of the plants and then the growth of the plant stop as in the case of heat treatment, but in theA. japonica which is closely affined to them and non-leaf-nodular plant, knobs are never formed either by antibiotics or by heat treatment.
2. Knobs are formed in proportion to the degree of concentration of the solution and the duration of treating time, and in the same method of treatment knob-forming ratio of theA. crispa are generally higher than that of theA. punctata and the size of the knobs of the former plant is larger.
3. The knobs are formed of epidermis, cortex and central cylinder, and no meristem and leaf-nodule-bacteria are recognized in any part of them by microscope, and the structures of them are almost as same as those formed by the treatment of heat.
4. It is probable that the formation of the knobs is due to a substance, secreted by the leaf-nodule-bacteria, which cluster on the growing point and die by the treatment of antibiotic or of heat, and that this knob-forming substance may also acts on the formation of leaf nodules to some extent.