Experiments were conducted to determine, if possible, the effect of various types of artificial manipulation of sweet-clover flowers when in full bloom on the production of seed. Only healthy, vigorous plants growing on well-drained soil were selected for these experiments. Before any of the flowers were open, the individual racemes were covered with tarlatan and labeled. (Fig. 5.) As soon as part of the flowers opened, the racemes were uncovered and after removing all flowers that were not open the open flowers were pollinated and the racemes re-covered. If the flowers of sweet clover are not fertilized they will remain open for two to three days, then wither, and in a short time drop. But after being fertilized the ovules enlarge very rapidly, and the corollas usually drop in about seven or eight days. Therefore, all fertilized flowers can be distinguished a few days after fertilization has taken place. Counts were made of the number of pods which formed in 10 to 12 days after pollination. An outline of the experiments is given in Table II. [Illustration: Fig. 5.--Individual racemes of white sweet clover covered with cheesecloth to protect them from insect visitation.] Table II.--_Treatment of sweet-clover flowers in the artificial-manipulation experiments._ ------------+--------------------------------------------------------- Experiment. | Method of pollinating the flowers. ------------+--------------------------------------------------------- A | Check--covered. | B | Check--open to insect visitation at all times. | C | A separate toothpick was used to spring the keel of each | flower on the raceme. | D | One toothpick was used to spring the keels of all the | flowers on a raceme. | E | Cross-pollinated. | F | Raceme rolled several times between thumb and finger. ------------+---------------------------------------------------------