742 



for each species. He further writes: (5, p. 414) »In den beschat- 

 teten Grotten , in welchen Lithoplujlhim Lenormaiuii, Callithamnion 

 elegans, Derbesia Lamoiiroiixii die aiissersten Grenzen der Vegetation 

 bezeichnen, verscliwinden diese Fornien schon vollstiindig in ge- 

 ringen Entfernungen voni Eingange. 1st es erlaubt aus den Befunden 

 an der Oberflache aiif das Verhalten in grosseren Tiefe zu schliessen 

 — die Berechtigiing dazu diirfte kaum bestritten werden konnen, 

 denn die Algenfornien sind an den entsprechenden OrtHchkeiten 

 theils ganz dieselben, theils nahe verwandt — , so muss die Licht- 

 intensitiit auch bier bei vorhandenem Pflanzenwuchs noch eine 

 ziemlich betrachtHche sein«. If it were possible to measure in some 

 way the amount of Hglit that reaches the algae growing in the inner- 

 most parts of the caves, this might certainly, as suggested by 

 Bert hold, serve as a measure of the intensity of the light at the 

 depth where tlie algae-vegetation disappears^. 



b. Sheltered Coasts. 



The Chlorophycece-Formntion. 



Here this formation is chiefly represented by an Enteromorpha- 

 association, but sometimes we also find others of the different asso- 

 ciations belonging to this formation on exposed coasts e. g. the 

 Prasiola s/zpz7a/a-association. 



The En/eron7or/)/2a-association grows highest, often somewhat far 

 above the highest w^ater mark and stretches down to a little be- 

 low it. It is often found on moist rocks and in clefts and cracks, 

 w^here fresh water oozes from the rock, and consequently it does 

 not form any continuous belt, but larger or smaller patches in these 

 places. It may moreover be found at the inner end of bays and in- 

 lets, where the bottom is covered with gravel or stones, and here 

 it may often partly replace the FucGcecp- formation. It is, for in- 

 stance, richly developed in the innermost part of Kalbak- and Kolle- 

 fjord, in Skaalefjord etc. Different forms of Enteromorpha intestinalis 



^ In order to try if any result might possibly be obtained, I used in 1900 

 Wynne's actinometer, which serves for photographic purposes to indicate the 

 exact term of exposure in a certain place (cf. Johs. Schmidt: Bidrag til Kend- 

 skabet om Skuddene hos den gamle Verdens Mangrovetrseer, Kobenhavn 1903, p. 11). 

 But in these caves, where the light is faint and the term of exposure consequently 

 long, the instrument proved less useful. With an instrument constructed by Dr. 

 Steenstrup (cf. Meddelelser om Gronland. 25, page 1) to measure the intensity 

 of the light, a satisfactory result might possibly be obtained. 



