Belkengren, R. O. (Oregon State U., Corvallis.)Growth and sexual reproduction of the moss Amblystegium riparium under sterile conditions.Amer. Jour. Bot. 49(6): 567–571. Illus. 1962.—Growth ofAmblystegium ripariumas primary or secondary protonemata, or as a leafy gametophyte under aseptic conditions, is reported. Yeast extract appears to be inhibitory for shoot growth but not for protonemal growth; it appears to cause the death of shoot buds on protonemata before they differentiate into leafy shoots, so that the organism grows as protonema only. Sexual reproduction of this organism in continuously illuminated cultures was induced by a CO2‐free period followed by addition of CO2or sugar. Senescence in a culture may also induce sporophyte formation presumably by interfering with photosynthesis or some other function.