MARINE ALGAL VEGETATION 147 



is generally known, the species has very strong haptera, often ar- 

 ranged in rows, which issue from the lower part of the stipe, so 

 that the haptera appear one above the other in vertical succession. 

 They then look like a vertical row of obliquely placed props, one 

 above the other; such rows issue in all directions from the stipe. 

 By this it must be understood that, as the plant grows, new hap- 

 tera appear, usually in the regular succession mentioned, until such 

 time as the plant attains its normal size. The development of the 

 haptera must necessarily keep pace with the rest of the growth, 

 because the larger the plant becomes so much the more is it moved 

 by the waves, and so much the stronger must the props become 

 if the plant is not to be torn up. The youngest props are the 

 longest, and are situated at the extreme (upper) end of the row. 

 That the growth of the organs of attachment is contemporaneous 

 with the increase in size of the individual applies also, of course, 

 to the other Laminar iacece , but scarcely anywhere is it seen so 

 distinctly as in this species. 



In its main features L. hyperborea behaves in Iceland at any 

 rate in S. and SW. Iceland in the same manner as it is recorded 

 by Borgesen (12, p. 755) to behave in the Faeroes. 



The Under- vegetation. No doubt an abundant under- vege- 

 tation occurs everywhere, chiefly formed of crustaceous algae as a 

 lower layer, and of branching or membranaceous Rhodophycece and a 

 few Phceophycece in addition as an upper layer. Here, as in the Fucus- 

 belt, it must be assumed that the under-vegetation is of no real 

 value to the upper; \vhile, on the other hand, the latter affords 

 protection to the under-vegetation in the Fucus-be\i against de- 

 siccation and too strong light, and in the Laminariacece-communily 

 against strong movements of the water. The subdued light caused 

 by the Laminaria fronds is, no doubt, also of importance in the 

 upper portion of the Laminaria-he\i , in so far, at any rate, that 

 the species with a more downward range may endeavour to attain 

 greater heights. In the lower portion of the Lamina ria-beli the sub- 

 dued light does not seem to affect the under-vegetation very much 

 which seems to thrive there just as well as in open places where 

 Laminariacece are absent; to have the waves moderated may be 

 beneficial to the under-vegetation, especially in shallow water. During 

 excessive ebb-tides opportunities may occur in many places of seeing 

 how the Laminaria fronds moderate the motion of the waves, that 

 is when this is not too violent, as, for example, when it approxi- 



10* 



