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An instrument was devised by the writers to determine the force requisite for detaching rice-grain from its rachilla. Both the breaking tensile strength, i.e. force strains along the direction of the rachilla, and the breking bending strength, i.e. force strains perpendicular to the rachill a , may be measured satisfactorily by the new instrument. The construction of the instrument is shown by figures in Tab. 1. With this instrument, the two strengths above mentioned were measured for ten varieties of rice taking any five ears of each, and the results obtained are shown in Table 1 (page 32) and Table 2 (page 33). The hardness of varieties for abscission is expressed in two ways, one by the mean values of both breaking tensile and bending strength of a number of grains of the variety as presented in Table 1 and Table 2 ; and the other by the percentage of grains which stand a certain amount of force as shown in Table 3 (page 34) and Table 4 (page 34). The results expressed by the percentage method nearly concur with the results obtained by the grasping method formerly adopted by many investigators. The ratio of the breaking bending strength to the breaking tensile strength is from 1: 1.6 to 1:3.1, and this provides important da t a to determine the tooth arrangement of the rotating drum of a rice thresher. The results of this study will prove useful not only in design i n g new type of rice threshers but also in testing those on market.