700 



days when the amount of clouds stands at 8. We must add that 

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

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

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

 time of the year, when it niight be most efTective; at the darker 

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

 is but very slight. 



Thus the faet, that the algæ -vegetation on the coasts of the 

 Færoes 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 Florideæ, but no vegeta- 

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



This is in agreement with Ro sen vinge (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 algæ- 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 algæ -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 

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

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

 is true that algæ 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 algæ fished up in deep water were certainly floating 

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

 Kjellman and Rosenvinge. 



On the whole, the faet, 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 algæ. As to the Bay of 

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

 in greater depths the Florideæ are certainly predominant, whereas 

 only a small number of Florideæ and Chlorophyceæ but especially 

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

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

 at the Færoes. I have found that the Laminariæ and other larger, 



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

 the extreme limit to which the algæ -flora reached was 160 metres in the middle 

 of the Mediterranean Sea, near Minorca. 



