I20 Dzvellers of the Sea and Shore 



pansion of the base of the plant Is the holdfast. This 

 latter, although corresponding to the root of a flower- 

 ing plant, does not, in the real sense of the word, per- 

 form the office of that member any more than the frond 

 functions as a flower or a leaf. Roots absorb the 

 nourishment for the entire plant. The nourishment 

 derived by algne from the substances held in solution 

 by the surrounding water is due to the work of every 

 individual cell composing the plant. In other words, 

 beyond the fact that it is in physical attachment to its 

 neighbors, each cell lives as a unit and without refer- 

 ence to the rest of the colony. 



Notwithstanding Its fundamental simplicity, the 

 diversity In the structure of marine algae is very great. 

 In the lower orders a single cell constitutes the plant 

 body. These forms are mostly microscopic. Next In 

 point of development are those like Cladophora, which 

 consist of single threadlike rows of cells. Then comes 

 Ulva, In which is found the earliest type of expanded 

 frond. Here the cells are arranged in a horizontal 

 surface forming leaflike or ribbonlike expansions. In 

 Enteromorpha there is a double layer of these cells 

 which separates, giving the seaweed a hollow, or 

 tubular, form. From here on the complexity Increases 

 until In Sargassum, or gulfweed, we see the most dif- 

 ferentiated of all marine plants. In this form there 

 are slender branching fronds bearing various kinds of 

 lateral members, some of which are like ordinary foli- 

 age leaves supported on stems; others are round air 

 floats resembling clusters of berries; and still other 

 branches bear remarkable sex organs. 



Not merely do the marine plants compare favorably 



