30 BRITISH MARINE ALG, 
active granules or spermatozoids, which, upon liberation from the anthe- 
ridia, swim about by means of ‘two vibratile cilia with which they are 
furnished, until they find the spores, around which they swarm, and 
upon which they finally settle, fertilisation of the spores being the result. 
The little ciliated bodies having performed their office, perish, and the 
spores begin to germinate and produce new plants of the species from 
which they sprang. " 
The process of development in the sporules of Fucus vesiculosus, and 
some others of this genus, is so extremely interesting that I will give a 
brief description of it in directing the reader’s attention to the accom- 
panying illustrations, Fig. 30 is a vertical cutting of one of the con- 
ceptacles of Fucus vesiculosus, showing the network-like filaments of 
which the fruit-bearing portion of the frond is composed, and the interior 
of the conceptacle or spore vessel ; the spores in various stages of develop- 
ment seated among projecting filaments, and attached to the wall cells of 
the cavity, the pore or opening above being their means of exit. Fig. 31 
contains more highly magnified portions of the filaments and cells, sepa- 
rated from the conceptacle, to show the gradual development of the 
spores, each of which is enveloped in a double transparent membrane. 
The under figure to the right represents the ruptured membranes, the 
spore having escaped into the water. In Fig. 32, on the left, is represented 
a spore fresh from a conceptacle, still enveloped in its double membrane, 
and exhibiting lines of separation into eight portions or sporules. The 
three next figures represent the complete separation and gradual develop- 
ment of the eight sporules, which assume by degrees a spherical form, and 
draw the inner membrane which incloses them upwards until it presents 
the appearance of a wine glass placed within a glass bowl. The central 
figure in the under line represents the sporules arrived at maturity, having 
ruptured the filmy membranes, and dispersing into the surrounding water. 
On the right is a sporidium, containing developing sporules and surrounded 
by spermatozoids. Fig. 33a represents a tuft of branched filaments from 
another conceptacle, several cells or joints of which are converted into 
antheridia filled with antherozoids or spermatozoids. The large round body 
(b) beside it is a spore, and ciliated granules are represented around and 
upon it. These minute objects are the spermatozoids, which under the 
microscope appear to be of oval form, but pointed at one end, having an 
orange spot in their centre, and being furnished with a filament at each end, 
by means of which they swim about until their brief existence terminates. 
On rocky coasts or wherever seaweeds abound, the various species of 
the genus Fucus occupy the greater part of the shore from high-water mark 
to some distance below half-tide level, and thus as they are the first to 
engage the collector’s attention, 1 will describe some of them at once. 
High up on the rocks, sometimes even above the reach of the tide, but 
moistened by the spray and dash of the waves, grows the small but 
pretty species F’. cancliculatus (Fig. 34). In some situations, where it is 
abundant and in fruit, the rocks upon which it grows present the most 
