700 



daj^s when the amount of clouds stands at 8. We must add that 

 the amount of clouds is the gredtest and fogs the most frequent at 

 the brightest time of the year. The direct influence of the sun on 

 the algae -vegetation is thereby still more diminished just at the 

 time of the year, when it might be most effective ; at the darker 

 time of the year the sun is so low in the sky, that its influence 

 is but very slight. 



Thus the fact, that the algae -vegetation on the coasts of the 

 Faeroes does not grow at any greater depth, may most likely be ac- 

 counted for by the small amount of sun and light. By dredging 

 in a depth of 25 fathoms, I have sometimes found some tole- 

 rably well developed specimens of some Floridece, but no vegeta- 

 tion whatever will by any means be found below 25 — 30 fathoms. 



This is in agreement with Rosenvinge (71, p. 233), when 

 he says : » As to the Arctic and the northern part of the Atlantic 

 Ocean, all investigators seem to agree in this, that below 20 fathoms 

 nothing but a scanty algae- vegetation is in any case to be found, 

 whereas it is very usual for the vegetation to reach as far down 

 as this.« In more southern countries the algae -vegetation will, 

 however, be found at much greater depths. At Capri in the Bay 

 of Naples, in clear water, Berthold (5, p. 414) found a luxuriant 

 algae- vegetation of deep-water forms at a depth of 120 — 130 metres, 

 that is, almost three times as far down as at the Faeroes^. It 

 is true that algae have been said to be found in very deep water, 

 even in arctic districts, but these statements are surely in so far 

 incorrect, as the algae fished up in deep water were certainly floating 

 and not fixed to any substratum, whicli has been pointed out by 

 Kj ell man and Rosenvinge. 



On the whole, the fact, that the intensity of light diminishes 

 and its colour changes as depth increases, is one of the most impor- 

 tant factors as to the distribution of the algae. As to the Bay of 

 Naples, Berthold points out (5, p. 415), that among algae growing 

 in greater depths the Floridece are certainly predominant, whereas 

 only a small number of Floridece and Chlorophycece but especially 

 the bulk of brown algae seek direct sunshine in shallow water. 

 This is, however, almost in agreement with what has been observed 

 at the Faeroes. I have found that the Laminarice and other larger, 



^ According to Sauvageau (77, p. 234 — 5, note), Rodriguez observed that 

 the extreme limit to wliich the algae -flora reached was 160 metres in the middle 

 of the Mediterranean Sea, near Minorca. 



