152 BOTANY. 
nary collector. There is therefore a good deal of diffi- 
culty involved in their study. The greater part of the 
material which the student secures for study is that which 
the storms have washed ashore from the deeper waters. 
314. The plant-body varies from small branching fila- 
ments, on the one hand, to expanded leaf-like growths 
showing a considerable degree of complexity, with the be- 
ginning of a differentiation of the cells into several kinds 
of tissues. All contain chlorophyll, which, however, is 
Fig. 75. Vice. 76. 
Fia. 75.—A Red Seaweed (Plocamium coccineum). About natural size. 
Fic. 76.—Tetraspores of Red Seaweeds. 4, of Lejolisia mediterranea; t, tetra- 
spores. B, of Corallina officinalis; ¢, tetraspores in a cup-shaped extremity of a 
ranch, 
generally hidden by the presence of a red or purple color- 
ing matter. 
315. The asexual reproduction takes place by means of 
spores, which, from almost always forming in fours, are 
known as tetraspores (4 and B, t,t, Fig. 76). These appear 
to replace the swarm-spores of other seaweeds, and may 
also be compared to the conidia of certain fungi; they are 
destitute of cilia, and are, as a consequence, not locomotive, 
