704 



beautifully iridescent, as Ihey are able to rellect certain rays of the 

 light that reaches them, and it has been proved by an experiment 

 made by Berthold (1. c. p. 419), that a vigorously iridizing specimen 

 of Chijlocladia kaliformis lost its iridizing power by being placed in 

 the shade, and recovered it by being once more exposed to the 

 light. A rich profusion of hairs is likewise probably of some im- 

 portance to the algæ, as a means of protection from the intensity 

 of the light. Several of the algæ growing in shallow water, especi- 

 ally in sheltered piaces, e. g. most of the species belonging to the 

 Stictijosij)hon-i\ss,oc'n\iion, are rich in hairs. It is however most 

 probable, that the hairs are in the first instance meant to serve as 

 organs of absorption and respiration, as pointed out by Rosen- 

 vinge^. Whether they are likewise capable of defending the algæ 

 against the dashing of the waves, as suggested by Henckel (Scripta 

 botanica XX, p. 105), I cannot tell. 



From what precedes it will be seen that I do not fully agree 

 wåth Simmons when he writes (p. 262): »Was den Einfluss der 

 Lichtintensitåt betrifft, so bin ich geneigt anzunehmen, dass man 

 besonders, vas die Florideen angeht, derselben zu grosse Bedeu- 

 tung hat zutheilen wollen. Wie will man nåmlich erklåren, dass 

 im nordwestlichen Norwegen , wo doch im Sommer nicht von ge- 

 ringer Lichtintensitåt die Rede sein kann, die noch dazu wåhrend der 

 Ebbe trocken begende Litoralregion so viele Florideen beherbergt?« 



There are always some Florideæ wiiich require a great deal 

 of light, and in the Færoes, where the light is far from strong, 

 and the direct insolation particularly slight, a great many Florideæ 

 may therefore easily thrive on the beach, even above the highest 

 water mark, without fading, whilst they fade in districts with 

 more light, are less numerous, and do not grow so far above the 

 level of the sea, except where local circumstances are especially 

 favourable. 



During a journey in Norway in 1904, I stayed a few^ days 

 at Christianssund, thus getting an op})ortunity of observing the 

 algæ-flora there. It was interesting to observe, how much less de- 

 veloped the littoral algæ-vegetation was here than on the Færoes, 

 the floral composition of the two vegetations, how^ever, being much 

 the same. The Florideæ were faded, light yellow to yellowish- 



^ Rosen vi lige, L. Kolderup: Sur les organes piliformes des Rhodomelacées 

 (Oversigt over det kgl. danslie Videnskabernes Selskabs Forhandlinger, 1903, Nr. 4, 

 p. 447—449). 



