— 177 — 



know moreover that the hollowness occurs at a somewhat later stage of 

 age, as young specimens botli in Greenland (Rosenv. Grj. Havalg.) and 

 in the Faeroes (Borgesen 1. c.) always have a solid stipe. As Rosenvinge^) 

 and Borgesen (1. c. p. 459) point out, the principal function of the hollowness 

 in the stipe appears to be that of making it fit to lift the great lamina 

 up from the bottom (cfr. also Farlow Mar. Alg. p. 93). Whether we in 

 the hollowness have to do with an adaptation to external conditions of 

 life, or a predisposition in the organism, we do not know. Regarding 

 the occurrence of the muciparous canals in the stipe, it may be said, 

 that in some cases it is most valuable as distinctive character, e. g. in 

 I J. hypei'borea, where the canals always are found, whereas the stipe of 

 L. digitata is always destitute of muciparous canals, but in L. nigripes it 

 cannot be depended upon as a distinctive character (see later p. 17S). It 

 has to be further investigated whether the muciparous canals in the stipe 

 of Laminaria longicruris are to be regarded as reliable distinctive charac- 

 ters or not, as their occurrence is highly variable individually or according 

 to age (Rosenv. 1. c). As yet known, they always occur in the lowest, 

 solid part of the stipe (Rosenv. 1. c. ; Guignard, Ann. sc. nat. VII. ser., 

 t. 15, p. 36). 



The specimens of Laminaria fteroensis with soHd stipe are not di- 

 stinguishable from Laminaria saccharina -). 



E. I eel. Fossarvik in BerufjorOur. 



N. Icel. Glsesibaer in EyjafjorSur (0. D.). 



Laminiiria nigripes J. Ag., emend. Rosenv. Grl. Havalg. p. 84:2. 



/9 atrofulva (J. Ag.) Rosenv. (1. c). 



Laminaria discolor, Laminaria nigripes f. oblonga Stromf. Algveg. 

 p. 43—44. 



The Icelandic specimens are entirely agreeing with the Greenlandic 

 plants. Smaller specimens have usually undivided lamina, but the lamina 

 of the greater plants is most commonly split into few and broad segments. 

 Only seldom I have met with plants, the lamina of which was split 



') L. K older up Koseuvinge: Om Algevegetationen ved (Troniand.s Kyster 

 in Meddel. om Grnnland XX, 1898, p. 2J1. 



^) In the description of Laminaria saccharina, C. A.Agardh (Synopsis Alg. scand. 

 Lund;e 1817, p. 17) says that the stipe is ,in speciminibus maximis tuhulosus". 

 Probably these large specimens have belonged to Laminaria longicnnis. In 

 Mar. Alg. p. *)3 Farlow utters in the description of Laminaria longicruris 

 that specimens resembling Laminaria saccharina, but witli hollow stipe, are 

 met with. As lie remarks nothing at all regarding tlie occurrence of muci- 

 parous canals in the stipe neither in these specimens nor in Laiuinaria 

 longicruris, we do not know where they are to be placed. 



