86 BRITISH MARINE ALG. 
produced on different individuals of the sarae species. A complete know- 
ledge therefore of the system of fructification of the red plants includes 
that of two individuals of the same species, one of which exhibits what 
is termed the primary, or conceptacular, the other the secondary, or 
granular, form of fruit. The sporiferous nucleus is described as con- 
sisting of numerous articulated or jointed filaments in distinct and 
variously formed conceptacles or spore-vessels, the joints of which become 
fertile or are transformed into spores. In no instance do the spores of 
the algz exhibit at any period of their development an approach to a 
rudimentary plant, as in the germinating seeds of the Phanerogamia, or 
flowering plants. They are found to consist entirely of a dense deep-red 
granular or starch-like matter, called ‘‘ endochrome,’’ enveloped in a 
nearly colourless skin or pericarp, consisting of two or three membranes. 
The secondary-form of fruit consists of tetraspores or four-parted seeds. 
These are produced from a division of the endochrome of certain privileged 
cells, the spherical mass of which they consist being separated into four 
parts, three of which are so placed within the enveloping membrane 
that the fourth part is completely hidden beneath them. Some forms 
of the tetraspore are, however, arranged so that all the four parts are 
visible at once. This occurs by transverse division of the endochrome, 
and is called ‘‘zoned”’ or ‘annular’? ; when divided by cross-lines into four 
equal parts, the tetraspore is cruciate; and when the division is by 
triradiate lines, and the parts are of unequal size, it is said to be 
ternately parted. Both forms of fructification are alike capable of 
reproducing their species; the tetraspores are, however, now generally 
regarded as gemme or buds, and thus they may be said to extend the 
life of the individual, rather than to reproduce the species. In the 
primary form of fruit the spores are rendered fertile by contact with 
antherozoids, which are produced in variously formed yellow-tinted cases 
called ‘‘antheridia,’’ found abundantly on plants in so many genera that 
they are doubtless developed in all, and always, of course, on plants which 
bear neither spores nor tetraspores. Further descriptions of the form and 
structure of the various fruit-bearing receptacles of the red plants will be 
given as each particular species is described and illustrated. 
I shall commence with a description of the plants which are included in 
the great series Desmiospermee, and follow the order in which they are 
classed in Professor Agardh’s most recent arrangement. Beginning, 
therefore, with the family Rhodomelacee, I shall describe the plants in the 
British genera which the Swedish professor includes in his order Chondriee, 
and these are Polyides, Lomentaria, Laurencia, and Bonnemaisonia. 
Polyides rotundus, now Polyides lumbricalis (Fig. 83), was formerly placed 
in the sub-order Spongiocarpew. On the southern British shores this is 
one of the common red weeds, being found in shallow rock pools between 
tide-marks in very great abundance. It is by no means a favourite species 
with ordinary collectors, being difficult to display effectively on paper, 
owing to its large disk-like root and its numerous forked, thick round 
