GABPOPHYTA. 



171 



some shade of red or purple which sometimes becomes ex- 

 ceedingly rich ; while for beauty of outline and delicacy of 

 branching they stand unrivalled among plants. 



305. To a great extent they grow in the deep water 

 below low-water mark, far beyond the reach of the ordi- 

 nary collector. There is therefore a good deal of difficulty 

 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. 



306. 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 difEerentiation of the cells into several kinds 

 of tissues. All contain chlorophyll, which, however, is 



Fig. 93. Fig. 94. 



Fig. 93.— a Red Seaweed (Plocamimn coccineum). About natural size. 



Fig. 94. — Tetraspores of Red Seaweeds. A^ of Le.iolisia mediterranea ; 

 t, tetraspores. B, oC Corallina oflSoinalis; t, tetraspores in a cup-shaped 

 extremity of a branch. 



generally hidden by the presence of a red or purple color- 

 ing-matter (phycoerythrin). 



307. The asexual reproduction takes place by means of 

 spores, which, from almost always forming in fours, are 



