Development of the Gametophyte in the Moss Tortella caespitosa

1. The effect of various factors leading up to development of the gametophore of Tortella caespitosa was investigated with special interest centered on auxins and nucleic acid derivatives. 2. Earlier work showing the inhibition of budding by high concentrations of auxins and the stimulatory effect of low concentrations was confirmed. 3. It was shown that (a) adenine and various related compounds can stimulate bud formation; (b) kinetin is especially effective in promoting cell division in buds but not in the protonemata; (c) a growth-inhibitory material is built up in the medium during the growth of the moss. 4. A mechanism is suggested for the formation of the gametophore.