A Monograph of the Genius Alaria. 49 



which appear early may be soriferous late in summer or early in 

 autumn, but the liberation of the zoospores begins, on an average, 

 in autumn between October and November. They then drop off 

 from the petioles, leaving verrucose scars on the stipe. During 

 winter, the upper sporophylls develop only a little. In early spring 

 they begin to develop quickly and the sori on them ripen con- 

 tinuously until the entire frond is uprooted in the middle of 

 summer. The sporophylls which are formed at a later period in 

 the life of the frond remain undeveloped and must follow the fate 

 of the frond, becoming useless before they can exercise their 

 proper function (Plates IX and X). 



How, then, does the blade pass through the winter ? Does 

 Alaria shed its blade periodically ? 



A. esculenta Gkev. has been the subject of this discussion 

 among the European algologists as the species is easiest accessible 

 to them for observation. Böegesen^) wrote a paper specially 

 devoted to the question and enumerates the views of many former 

 writers. Beside those mentioned by him, Dawson Turnek"'^) remarks 

 that Fucus esculentus is perennial, though he does not touch the 

 subject in question directly. Eupeecht^) repeated the words " ein- 

 jährige Exemplare " in describing the North Pacific Alaria. It 

 may be taken as evidence that he believed the Alaria plant to live 

 more than one year. Setchell and Gardner^) in their joint work - 

 report the presence of the " rings of growth " in the stipe of A. 

 valida. Rosenvenge^) does not actually say that Alaria is perennial, 

 but he illustrates the shedding of the old blades in his specimens. 



1) BöEGESEN : Note on the Question whether A. esculentd sheds its Lamina, &c. 



2) Turner: Historia Fucorum, Tab. 117. 



3) RupEECHT : Tange des och. Meeres, p. 355. 



4) Setchell and Gardner : Alg. N.-W. Amer., p. 278. 



5) EosENA'ENGE : On the Marine Algae from Northeast Greenland, p. 113, fig. 5. 



