Lymphatic pressures and the flow of lymph

1. Peripheral and central lymphatic trunks have been cannulated in 23 greyhounds and side pressures recorded. 2. The thoracic duct pressure was always higher than the jugular venous and peripheral lymph pressures. Groin lymphatic pressure was higher than at the foot in the resting dog. 3. Skin massage, foot movement, and the calf muscle pump all increased the peripheral lymphatic pressures. Rhythmical contractions of leg lymphatics were recorded only in young pigs. 4. The inferences from these observations are discussed, and it is suggested that lymph flows by energy from three mechanisms—a peripheral muscular pump, an abdominal and a thoracic pump.