For a study of the distribution of antibiotics in the seeds and plant organs, the method recommended is that of applying a layer of warmed agar to the samples being tested and diffusing the test organism through it. Treatment of the seeds for 20-30 minutes with antibiotic solutions at concentrations of 50, 100, and 1000 units/minute shows quick penetration of the antibiotics into the seed coat and embryo and their retention there for a long time. Penicillin disappears comparatively rapidly, but blomycln, terramycln, and streptomycin are retained considerably longer. Antibiotics are retained longer in the seeds of pepper and eggplant and not as long in those of sainfoin, cotton, and tomatoes. Penicillin accumulates selectively in the leaves of vegetable seedlings unlike biomycin and streptomycin, which are found preponderantly in the plant roots.