The pollen of Trifolium pratense is physiologically different from that of T. hybridum and T. repens in respect to behavior toward sugar solutions. The only function of the sugar solution in the case of the pollen of T. hybridum is the controlling of water supply. The germination of the pollen of T. pratense is delicately adjusted to water absorption. The results of the investigation show that the stigma produces no secretions which influence pollen tubes. The nature of the pollen demands no other function of the stigma in its germination than the control of the water supply. The pollen in self-pollination germinates readily on the stigma, but the tubes traverse the style much more slowly than in cross pollination.