1. A survey of the available literature on sexual reproduction in Vaucheria from Vaucher down to the present time is given. From this survey it appears that the sperms have been observed in all species investigated, with the possible exception of V. geminata (there is some doubt about the plant studied by Schenk being V. geminata). 2. The development of the sperms and their discharge were observed in V. sessilis, V. pachyderma, and V. aversa. In V. geminata the development of the sperms and their movement in the antheridium were observed, but the discharge of the sperms was not seen. In the species in which discharge was observed this usually occurred at night, sometime after midnight. The present observations on the development of the sperms corroborate those of Pringsheim, Walz, Woronin, Oltmanns, and Heidinger. 3. In V. sessilis the "Wanderplasm" initiates the formation of the oogonial branch, but as soon as the oogonium is about mature the "Wanderplasm" migrates back into the main branch. 4. In V. gem...