SECT. IT. ENTEROMORPHA. 223 



endochrome, which is enclosed in little cells placed ac- 

 cording to a definite plan within the transparent and 

 tubular joints of the filaments. In the Bangia fuscopur- 

 purea, whose blackish purple tufts, several inches long, 

 cling closely to the rocks near high-water mark, the 

 tubular joints contain rows of minute colour cells radi- 

 ating from a centre. In the narrow filaments there is 

 but one colour cell in a joint, but in the broader filaments 

 there are from three to five, forming a tesselated line 

 across it. In this plant one spore is produced in each 

 joint. The Bangia ciliaris forms a scarcely perceptible 

 rosy pink fringe of hair-like jointed filaments on the Zos- 

 tera marina, and also on other Algae. The filaments are 

 not more than the tenth or fifth of an inch long, conse- 

 quently their joints are most minute, yet the microscope 

 shows that they contain from two to three colour cells set 

 as if radiating from a centre, and that the granular en- 

 dochrome in each cell is converted into two zoospores. 

 The Bangia ceramicola, which forms purplish pink tufts 

 on small Algse in rock pools, differs from both of the 

 preceding. The joints of its filaments are once or twice 

 as long as they are broad, and contain colour cells like 

 long upright lines. By aided vision zoospores are seen 

 to be formed within the linear colour cells, then the 

 cells run together into a globular mass, which bursts 

 through the cell wall, leaving the joint empty. The 

 whole genus is soft and sometimes gelatinous. 



The Enteromorpha genus is characterized by a cylin- 

 drical and tubular stem and branches. These plants 

 form two groups, one whose filaments and branches 

 swell from a narrow base upwards and terminate in a 

 blunt extremity, while in the other group the tips of 

 the branches are pointed. The Enteromorpha intesti- 

 nalis, which is an inhabitant of many seas, has a thin 

 membranous, tubular, cylindrical, and unbranched stem, 

 inflated upwards into a broad round head, being more 



