Several workers have observed, in Europe and elsewhere, that Gracilaria verrucosa is a more conspicuous component of the flora in the summer months (Cotton, 1912, p. 134; Rosenvinge, 1931, pp. 602–6; Gibb, 1939, p. 378; Causey, Prytherch, McCaskill, Humm & Wolf, 1946; May, 1948), with the natural inference that its growth rate is greater in that season. However, the quantity present on the shore at any time depends also on the rate of defoliation by the waves. This will be higher in winter. Observation under more controlled conditions was therefore considered desirable.