MELANOSPERME®. 29 
while he pursues his fishing. The alga which attains the greatest length 
on the British coasts, is that remarkable plant called Chorda filwm 
(Fig. 49), or sea rope, often found in deep water, from 30ft. to 40ft. in 
length. Many an expert swimmer has lost his life while bathing among 
its slimy but tenacious fronds, whence its popular name in some loca- 
lities of ‘‘ dead men’s lines.”’ 
Though most of the Melanosperms are olive coloured, especially when 
fully grown, many of them turn to a pale green, and others to a bright 
verdigris green, either when decay sets in or in drying. ‘This is par- 
ticularly observable in the young plants of the various species of Laminaria, 
all the Desmarestiew, several species of Ectocarpus, and some others, a 
peculiarity which at first misleads young collectors, who imagine from 
the green tint of their mounted specimens that they have gathered 
Chlorosperms ; however, experientva docet. 
As all works on marine algze commence with descriptions of the various 
species of Sargassum, or gulfweed, some mention of this remarkable plant 
will naturally be expected here ; but it is not a British seaweed, and is 
only occasionally wafted to these shores, collectors rarely meeting with it 
anywhere but on the south coast of Cornwall, and even there mere frag- 
ments or seaworn specimens only are picked up among the rejectamenta 
of the sea. There are a large number of species of Sargassum in various 
parts of the world, but that which is known as “gulfweed,”’ is the floating 
species Sargassum bacciferum, or berry-bearing sargassum, the so-called 
berries being really air-vessels which serve as floats to support the plant 
on the surface of the water; and it may be remarked that the vast fields of 
seaweeds which were first described by Columbus when he crossed the 
Atlantic, and which seriously impeded the progress of his small vessels, 
are met with at the present day in very nearly the same situation. These 
floating plants are not propagated by spores, but by gemme or buds; 
sprouts, in fact, that are thrown out from all sides of the old plant, thus 
continuing the life of the plant rather than reproducing it; those species 
only which grow on rocks being propagated by spores, which are produced 
in clusters of stalked receptacles. 
The genus Fucus differs from all other orders of melanosperms in having 
their spores or reproductive bodies attached to the walls of conceptacles 
or spore cavities sunk within the substance of the frond, and communi- 
eating with the surface by means of a pore or minute opening. In F. 
vesiculosus (Fig. 37) these receptacles are filled with a slimy or gelatinous 
matter which, under the microscope, is found to be a beautiful network of 
jointed fibres (Fig. 30), and within the round hollow conceptacles which are 
immersed in the jelly-like masses, the spores in some, and antheridia in 
others, are produced. The endochrome, or whatever the spores consist of, 
is at first simple, or consisting of a single body or substance, but it 
subsequently divides into two, four, or even eight sporules. The antheridia 
are borne on branched filaments, which are also attached to the walls of 
conceptacles, but on separate plants, and these antheridia are filled with 
. 
