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ring to his herbarium a single plant caught in the transition state ? 

 Nay, are there any of the laws under which the vegetable kingdom 

 exists better known than those laws which fix certain species of the 

 Algae to certain zones of coast, in which each, according to the over- 

 lying depth of water and the nature of the bottom, finds the only ha- 

 bitat in which it can exist ? The rough-stemmed tangle (Laminaria 

 digitata) can exist no higher on the shore than the low line of ebb 

 during stream-tides ; the smooth-stemmed tangle (Z. saccharina) 

 flourishes along an inner belt, partially uncovered during the ebbs of 

 the larger neaps; the forked and cracker kelp-weeds {Fucus serratus 

 and F. nodosus) thrive in a zone still less deeply covered by water, 

 and which even the lower neaps expose. And at least one other spe- 

 cies of kelp-weed, the Fucus vesiculosus, occurs in a zone higher 

 still, though, as it creeps upwards on the rocky beach, it loses its 

 characteristic bladders, and becomes short and narrow of frond. The 

 thick brown tufts of Fucus canaliculars, which in the lower and 

 middle reaches of the Lake of Stennis I found heaped up in great 

 abundance along the shores, also rises high on rocky beaches, — so 

 high in some instances, that during neap tides it remains uncovered 

 by the water for days together. If, as is not uncommon, there be an 

 escape of land-springs along the beach, there may be found, where 

 the fresh water oozes out through the sand and gravel, an upper ter- 

 minal zone of the Confervas, chiefly of a green colour, mixed with the 

 ribbon-like green laver (Ulva latissima), the purplish -brown laver 

 (PorpJiyra laciniata) , and still more largely with the green silky En- 

 teromorpha (E. compressa). And then, decidedly within the line of 

 the storm-beaches of winter, — not unfrequently in low sheltered bays, 

 such as^the Bay of Udale or of Nigg, where the ripple of every higher 

 flood washes, — we may find the vegetation of the land, — represented 

 by the sentinels and picquets of its outposts, — coming down, as if to 

 meet with the higher-growing plants of the sea. In salt marshes the 

 two vegetations may be seen, if I may so express myself, dovetailed 

 together at their edges, — at least one species of club-rush [Seirpus 

 maritimus) and the common salt-wort and glass-wort (Salsola Kali 

 and Salicornia procumbens), encroaching so far upon the sea as to 

 mingle with a thinly-scattered and sorely-diminished Fucus, — that 

 bladderless variety of the Fucus vesiculosus to which 1 have already 

 referred, and which may be detected in such localities, shooting forth 

 its minute brown fronds from the pebbles. On rocky coasts, where 

 springs of fresh water come trickling down along the fissures of the 

 precipices, the observer may see a variety of Rhodomenia palmata, — 



