The data obtained from the two plants at Arlington that were protected from night-flying insects may also be cited here, as the results of that experiment show that night-flying insects are not an important factor in the production of sweet-clover seed, and, further. because they were growing under the same conditions, in the same plat, and were approximately of the same size. These two plants produced a total of 544 racemes, with an average of 20.9 pods each. The number of pods to the raceme varied from to 86. EFFICIENCY OF CERTAIN KINDS OF INSECTS AS POLLINATORS OF SWEET CLOVER. In order further to test the self-sterility of sweet clover and to determine the relative efficiency of night-flying and of different kinds of day-flying insects as pollinators of the flowers, a number of cages covered with cheesecloth, glass, or wire screen having 14 meshes to the linear inch were placed over plants at Arlington. Va., and at Ames. Iowa, in July and August. 1916. The bases of the cages were buried several inches in the ground, so that insects could not pass under them. Cheesecloth was used to cover most of the cages and was made into sacks of such a size that they could be put on or removed from the frames of the cages without difficulty. It was stretched tightly over the frames and fastened to their bases with laths. A cage having two sides and the top of glass but with ends covered with cheesecloth to permit ventilation was used at Ames to protect a number of plants from insect visitation at all times. The purpose of this cage was to determine whether the partial shading of the plants in the cages covered with cheesecloth would have any effect upon the setting of seed. The cage covered with wire netting having 14 meshes to the linear inch was used to determine the efficiency as pollinators of sweet clover of insects so small that they could pass through openings of this size. The plants used in the experiments at Arlington were growing close to the center of a field of sweet clover. Volunteer plants in a field that contained only a scattering stand were used at Ames. The cages were placed over the plants in all of these experiments before any of the flowers opened, and the work was continued until they were through blooming. PLANTS SUBJECT TO INSECT VISITATION AT ALL TIMES. A plant subject to insect visits at all times and growing in the same plat as those inclosed in the cages at Arlington was selected as a check to those inclosed in the cages during their entire flowering period or for only a portion of it. This plant, which was in bloom at the same time as those inclosed in the cages, produced 196 racemes with an average of 20.4 pods each. As all of the racemes were collected and as those on the lower portions of the plant were smaller than those on the upper branches, the average number of seeds per raceme is much lower than it would have been if only the larger racemes had been collected.