28 CARL SKOTTSBERG, MARINE ALG^ 1. PH^OPHYCE^I. 



dariacese. Large fertile fronds were gathered from November to February; låter they 

 decay and disappear. There is no trace of them during the winter, but in Jnly new 

 ones begin to appear; such were figured by the writer in 1907. 



The »Chordaria»-shoots are upright in the water. but not rigid, and prostrate 

 when uncovered. They attain 16 cm. The main axis is 1 — 1.5 mm thick, but thinner 

 at the base. Except the basal part it bears numerous branches, generally not över 

 3,5 cm long, very thin and nearly alvvays simple. Young specimens show that the 

 branches are developed in basipetal order: the zone of more vivid secondary grovvth is 

 suprabasal, but not too strictly localized, as young branches also spring from be- 

 tween the older ones. Sometimes they are fasciculate. In a couple of specimens the 

 main axis was found to be forked. 



The horizontal thallus, where the fertile »cups» and the vesicles are formed, 

 at first consists of a thin crust or cushion with a more or less lobed margin, the lobes 

 forming processes, which branch repeatedly, often di-trichotomously but also rather 

 irregularly. New branches spring from above these and various thalli meet and 

 become fused, so that finalty very large, flat or more coralloid crusts are formed, 

 with the innumerable branches quite inseparable without getting torn to pieces. The 

 branches are flat or cylindrical. The cups are situated at or near the end of the 

 branches; in any case, the cup represents the end of a small branch, which, after 

 the circular wall has been formed, becomes transformed into the fertile »Chordaria»- 

 shoot. The structure of this is tj^pical, as will be seen from my figure 12 b. The 

 axis is solid or becomes hollow with age. The assimilators are about 75 |x long, gen- 

 erally three-celled with swollen endcell, measuring 15 to 18 [x across. Hairs were 

 rare but found in all plants examined. The sporangia are obovate, 30 — 45 x 15 — 1 8 jx 

 and contain numerous spores. 



An examination of the young tip of a branch in the act of forming a fertile 

 frond shows that growth is arrested in a central circular area, from what results the 

 formation of a depression, surrounded by a thick margin. From the centre of the 

 depression springs the »Chordaria»-shoot. I have searched my material for the young 

 stages: it seems that a group of firmly joined filaments arises, with swollen end-cells, 

 and bearing a superficial coat of Chordaria-assimilators. A longitudinal section 

 through a young fertile branch shows that the whole plant has the monosiphonous, 

 ectocarpoid structure, essential to all members of the Chordariacese. 



If the bladders, the »Colpomenia-Sprosse» as I called them in 1907, really 

 belong to Ccepidium, they must show the same structure. And they do. I arrived 

 at the conclusion that the bladders were swollen and hollow protuberances on the hori- 

 zontal thallus, and not another alga, intimately connected with Ccepidium. The 

 bladders bore gametangia and resembled Colpomenia in most points. For this reason 

 I transferred Ccepidium to the Punctanacese, for we must remember that the ma- 

 ture »Chordaria»-shoots were unknown. In my new material the development of 

 the bladders could be followed with, as far as 1 can see, absolute certainty. They 

 originate as small solid warts. The greater part of a lobed and branched crust is 

 not seldom transformed into a large bladder, covering the still solid parts, which 



