18 Mindeskrift for J. Steenstrup. XXXII. 



At first I wish to repeat here again the statement that a form exactly agreeing 

 with S. natans and its varieties has never been found at any shore, nor do 1 believe 

 that such form will be found. It is namely a well known faet that loose and floating 

 algæ gradually change their appearance; they grow as if without regulation, getting a 

 quite differing shape, often with numerous proliferations, and being sometimes quite 

 deformed. I need only to refer to the highly diflerent and peculiar appearance of 

 the loose-Iying formå scorpioides of Ascophylluni nodosum '), in comparison with the 

 typical form, as already pointed out by Reinke"). Unless the development was known, 

 it would be impossible to imagine the faet that these two forms actually belong to 

 the same species. Rosenvinge-') mentions the difference in habit of several algæ 

 occurring in his "loose-lying Algæ-formation" as compared with the attached forms; 

 in my treatise on the algal vegetation of the Færoese coasts^) I have pointed out 

 that many algæ, in slieltered piaces, and most often loose-lying, have quite a different 

 appearance from the specimens attached and growing in more open localities. And 

 in regard to loose-lying algæ from the Adriatic Sea Schiller'') in an interesting 

 paper writes p. 64: 



"Durch oftmalige und durch mehrere Jahre fortgesetze Beobachtungen konnte ich micli 

 iiberzeugen, das diese Algeu wachsen, niemals fruktifizieren, sich lediglich vegetativ vermeliren 

 und starken morphologisclien und physiologischen Verånderungen unterliegen." 



and in a special part: "Morphologische und habituelle Verånderungen der Migrations- 

 algen" very detailed descriptions are given of the great change in habit of the loose- 

 lying algæ as compared with the fixed forms. 



Owing to these facts 1 feel convinced that the floating Gulfweed has an appearance 

 very distinct from the original, attached form. 



') This form is destitute of vesicles and lies on tlie bottom; detached Ascophyllum carried 

 out at sea sinks therefore most probably soon. 



-') Reinke, J., Algenflora der westlichen Ostsee deutschen Antheils. Kiel 1889, p. 33 — 34. 



^) Rosenvinge, L. Koldebup, Om Algevegetationen ved Grenlands Kyster. Meddelelser om 

 Grønland, XX, 1898, p. 218—220. 



*) Borgesen, F., The Algæ-vegetation of tlie Færoese coasts (Botany of the Færoes, Part 

 III, 1905, p. 697). 



■■') Schiller, I., fiber Algentransport und Migrationsformationen im Meere (Internationale 

 Revue der gesaminten Hydrobiologie und Hydrographie, Bd. II, 1909). When Schiller calls the 

 loose-lying algæ-formation "Wanderformation" or "Migrationsformation" and the loose-lying algæ 

 "Migrationsalgen" I do not think that these names are very successfully chosen. Certainly the 

 algæ do becoine dispersed by currents or by wind, carried to sheltered piaces, far away from 

 their original stations, but this way of transportation is of course purely mechanical, thus by no 

 ineans intimating "migration". When arrived to such sheltered piaces the Algæ reinain there, 

 and gradually acquire the different aspect. Finally when Skiller at the same time considers the 

 Gulfweed in the Sargasso Sea to represent a Migrationsformation, I can not agree with him since 

 the Gulfweed, as I have pointed out above, propagates by vegetative division in tlie Sargasso Sea 

 itself, where it rests for the balance of its life. 



