Careful inspection of a number of sweet-clover fields in Iowa and Illinois in the autumn of 1916 indicated that many plants were unable to obtain sufficient moisture for the proper development of their flowers. Examination of flowers that aborted shortly after reaching their mature size showed that the anther sacs had not burst, even though the pollen grains were mature. Apparently for the same reason many immature pods aborted. The precipitation for July, 1916, in Livingston County, Ill., where the sweet-clover seed crop suffered materially for lack of moisture, was 3.2 inches less than normal, while the temperature was 4.5° F. above normal. In August the precipitation was 0.96 of an inch below normal and the temperature 4.2° F. above normal. At Ames, Iowa, the precipitation was 3.54 inches below normal and the temperature 5.4° F. above normal in July. Both the precipitation and temperature were about normal at Ames in August, but most of the precipitation fell before the experiments were commenced. In north-central Illinois the seed production of sweet clover was very irregular. Some fields produced an abundance of seed, while a large percentage of the pods on the plants in other fields near by, where the thickness of the stand, size of the plants, and conditions in general were approximately the same, aborted. It was evident that all stands producing a good seed crop were growing on well-drained soil and that those which were not yielding satisfactorily were on poorly drained land. It is well known that sweet clover will produce deep taproots only when the plants are growing in well-drained soil and that a much-branched surface root system will be formed on poorly drained land, and especially when there is an excess of moisture or a high water table during the first season's growth. During this droughty period in 1916 the upper layer of soil became so depleted of moisture that the plants with surface root systems were unable to obtain sufficient water to mature their seed. On the other hand, the lack of precipitation and the high temperatures did not affect the moisture content of the subsoil sufficiently to interfere with the normal seed production of deep-rooted plants. According to Lutts (22, p. 47) this same condition was found to be true in Ohio in 1916.