152 



BOTANT. 



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 v^hich 

 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 



Fio. 75. Fig. 76. 



Fia. 76.— A Red Seaweed (Plocamium coocineum). About natural size. 



Fio. 76.— Tetraspores of Red Seaweeds. A, of Lejolisia mediterranea; t, tetrft- 

 spores. B, of CoralUna officinalis ; t, tetraspores in a cup-shaped extremity of a 

 brancli. 



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 {A 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. 



