The main objective of the BAH (Biologische Anstalt Helgoland) was to gain control over the induction of sporogenesis in Laminaria digitata and to reduce the time it takes individual algae to start reproduction. Compared to the occurrence of double prime sorus double prime (sporogenous tissue) on L. digitata in the field, the experiments showed the acceleration of sporogenesis by 5 months under certain conditions in the laboratory. Pieces of young tissue developed sorus under various light regimes and a range of temperatures. In contrast to L. digitata, L. saccharina tissue required short-day conditions for sorus formation that was obtained at least two months ahead of natural occurrence. The minimum plant age of L. digitata facilitating sporogenesis was found to be 7.5 months at the start of the experiment, with the first sorus showing after 5 weeks. This corresponds to our findings in mass cultures of local L. digitata which have been undertaken close to the island of Helgoland. They rendered early formation of sorus on 8.6 months old sporophytes as calculated from the zoospore stage, contrasting to 18 months in natural populations and reconfirming findings in mass cultures at CEVA, Pleubian. The youngest tissue forming sorus in the experiment was collected from a second year plant and was only 14 to 28 days old. Older pieces of the thallus preceeded younger pieces in sorus formation. Nutrient enriched seawater accelerated sporogenesis compared to pure seawater, but had the disadvantage of facilitating luxuriant growth of epiphytes. The viability of the laboratory raised spores was tested and a completely normal developement of young sporophytes obtained. 340 m of culture string were densely seeded with L. digitata spores from 12 disks with an original diameter of 23 mm. double prime Phycotrons double prime , designed by IFREMER, Nantes, and employed at Helgoland showed that in parallel experiments isolated disks of thallus preceded whole algae in the formation of spores by far. The same was found in a different experimental setup. To investigate the reasons for the different behaviour of isolated pieces versus whole thallus in terms of sporogenesis, experiments were conducted at CNRS-CEOBM, Roscoff, and at the BAH on Helgoland. An oxidative stress following the punching out of thallus disks was tested, but could not be proven. Addition of various oligosaccharides to disks resulted in burst-like releases of H sub(2)0 sub(2) by disks.