52 CARL SKOTTSBERG, MARINE ALGJE 1. PH^OPHYCE^ 



formation of thin walls takes place, which stain with Lichtgriin like the other walls. 

 I have seen them clearly enough in some cases (fig. 20 d). This formation of cell 

 walls, as well as the rapid division of the cell content, makes it rather improbable 

 that we have to do with gametangia. My hypothesis is that we have chains of 

 sporangia and that when the eight spores are formed there is a reduction of chromo- 

 somes. But we cannot tell whether the spores are asexual as in the Laminariacese 

 or sexual as in the Fucacea?. In the former case we must expect a microscopic 

 sexual generation. The number of spores is certainly very small, but in Chorda 

 there are only 16 (Kylin, Entwickelungsgesch.). Kylin, on good reasons, assigns to 

 Chorda the rank of an order; Chordacese and Laminariaceae form his group Lami- 

 nariales. No Laminariacea is known with such a small number of spores, while 8 

 eggs may be considered as typical in the Fucacese. The mode of growth in Ascoseira 

 has remained unknown; the likeness with Lessonia may be superficial, while the 

 conceptacles are decidedly fucacean in character. It seems better to bring Ascoseira 

 to the Fucales and to regard the spores as equivalent to the sexual bodies of Fucus. 

 Only one kind has been found; male and female ones may be all alike, or there may 

 exist plants with another kind than the one I have found. If Ascoseira has sexual 

 spores of two kinds, but morphologically alike, it as an interesting primitive type. 



In the conceptacles we generally find the sporangial chains broken up and the 

 sporangia lying loose (fig. 20 f). The young ones are almost hyaline on unstained 

 material, while the ripe ones are yellowish-brown, but I have not obtained a good 

 view of the chromatophore. The size of the ripe sporangia is 15 — 21 x 8 — 12 ji. The 

 spores hold together quite firmly but are separated by pressure. I have never seen 

 an empty sporangium; it seems that the whole breaks up into 8 parts under dissolu- 

 tion of the thin walls, but further and better material is necessary. It is even pos- 

 sible that the entire sporangium passes out of the narrow canal, though it must 

 remain unsettled by what means such a movement is effected. The arrangement 

 of the spores in the sporangium is illustrated in fig. 20 e. 



New researches are urgently needed before we shall be able to understand 

 Ascoseira. 



Distribution: S. Georgia, Graham Land. 



F u c a o e se . 

 Durvillea Bory. 



In his »Phycese novse vel minus cognitae» Areschoug dealt with Durvillea in 

 some detail. All the south american forms were included under one species. Among 

 the numerous specimens examined by Areschoug eight forms were distinguished 

 which we shall discuss briefly. a is apparently a young D. antarctica; b and c are 

 like D. Harveyi, but c is partly inflated; to this Areschoug b rings Lam inaria ccepe- 

 stipes Mont. = Z). Montagnei Kutz. ; d is typical D. antarctica; e is a transitional 

 form, / and g belong to D. antarctica; h is D. Harveyi. 





