KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 61. N:0 || 



53 



Since I have had ample opportunity to study these algae in their natural 

 surroundings, I shall propose that we make a distinction between the two extremes, 

 which we call D. antarctica and Harveyi. D. antarctica grovvs on exposed, rocky 

 coast, on steep cliffs, often in narrow crevices where the surf is very violent. During 

 dead low water it hängs down from the rocks, with the long whip-like segments 

 washed by the spray or, in calm weather, almost dry for a short while. At high 



Fig. 20. Ascoseira mirdbilia: a hair, X 360; b chain of sporangia, X 360; C base of sporangium-chain, X 900; d 

 formation of spores, X 000; e three sporangia, X 900; f length section through conceptacle canal, X 180; g mouth of 



conceptacle seen from surface, X 180. 



water the whole plant is violently tossed about in the breakers, in stormy weather 

 with a tremendous force, that would tear the strongest frond to pieces were it not 

 split up into numerous laciniae, elliptical or circular in section. The colour of the 

 strongly »inflated> frond is dark greenish brown in living specimens and reddish 

 brown in the dead and dried ones. 



D. Harveyi is also an inhabitant of the exposed coast but grows in places 

 where the force of the breakers is checked as they have to pass över a more or less 

 broad shelf with shallow water before reaching the place where Durvillea grows. 

 At low water it is more or less exposed to the air and slowly washed by the waves 

 or even dry for a short while. It also occurs in the lower tide-pools. The frond 

 is compact, leathery and entire or nearly so; the colour of the living plant is yellow- 

 ish brown, that of the dead and dried almost black; thence the unnatural colour in 

 Flora Antarctica. 



I have also observed an intermediate form, growing in more agitated water. 



