SECTION II. 
MELANOSPERMEA. 
Olive Seaweeds. 
THE olive seaweeds, though much less numerous than the red, greatly 
exceed the green plants in numbers as well as in size; and, although some 
few of the red and green weeds are used as articles of food, and for other 
purposes, the Melanosperms bring by far the largest revenue to man. As 
manure for the land nearly all kinds are equally serviceable, but in the 
manufacture of kelp, which is a coarse or impure carbonate of soda, the 
Fuci or large rock weeds, are especially valuable, while the various species 
of Laminaria, in combination with the Fuci and other olive weeds, yield 
mannite and a large amount of iodine. On the west coast of Ireland the 
poor peasants are almost entirely dependent on the seaweeds which are 
cast ashore, for manure in the cultivation of their potatoes; and in the 
Channel Islands, the ‘‘ vraicking season”’ (as gathering seaweeds is called 
there) assumes the importance of a hop picking in Kent. In Norway, 
and in the north-west of Scotland and Ireland, some of the Fuci, such as 
F. serratus (Fig. 36) and F. vesiculosus (Fig. 37), are dried as winter 
provender for horses and cattle. On the south coast of Devon I have 
occasionally, while ont on my algological excursions, seen a herd of cows 
descend from the fields to the shore and browse on the Fuci with 
great avidity. 
The name “ Melanosperm’’ or “black seed” is applied to that large 
class of olive-brown plants, several species of which, such as the well- 
known Fuci or Kelp weeds, are characteristic of most rocky shores ; 
they form the leading feature of marine vegetation from high-water mark 
to half-tide level, while the Laminariw or great oar weeds, are rarely 
uncovered by the tide, but vegetate from extreme low-water mark to 
several fathoms deep, where they form a broad belt of marine vegeta- 
tion, usually termed the Laminarian zone. In clear weather, when the 
water is undisturbed, the long strap-like fronds of these seaweeds may 
be seen waving to and fro as the observer passes above in a boat. 
The gigantic alge of the ocean depths are all olive coloured, and to 
these our largest Laminaria is but a pigmy, for the great Nereocystis of 
the Pacific Ocean is said to have, at maturity, a stem 300ft. long, 
bearing at its summit a huge barrel-shaped air-vessel, terminating in a 
tuft of about fifty forked leaves, each of which is above 40ft. in length. 
The large air-vessel supports this immense frond in the water, and here 
the Lulra marina, or sea otter, rests himself or hides among the leaves, 
