ITiiless the writer’s survey of tlie aiiatomical aiid embrplogical bibliographies has beeii faulty, it may be claimetl tliat tlie mode of origin aiid developmeiit of tlie venous valves has iiot been studied before. Writings touching 011 tlieir iiiceptive and formative periods were iiot found, if wc exclude scant reference to tlie eustachiaii aiid tliebesian valves of tlie heart. This seems strange, in view of the voluminous literature on tlie topographical arrangement, mechanism, aiitl fuiictioiial sigiiificaiice of these organs arid tlie familiar clcscriptions of them in most aiiatomical aiid physiological compendia. Tlic clinical interest that attaches to the coiiditioii of veiioiis varicoses and tlie century-long and professioii-wide tliscnssioiis of tlie possible factors involved in tlieir procluction slionlcl liavc heeii sufficiciit ere now, we had supposed, to stimulate an injury into the genetic history of the valves. The writer’s atteiitioii to this aspect of vascular organization was inspired by circumstarices quite different. His observatioiis 011 the establislimeiit of the gateways in tlie amphibian lympli licarts aiid tlie finding of simple yet ingenious methods iiilierent in tlieir creation, led directly to tlie question coiiccniiiig the geiiesis of the lymphatic valves in man, and indirectly to that of similar strnctnres in tlie reins.