90 SEAWEEDS 



CHORDARIACE.E. 



General Characters. The Chordariacece are a some- 

 what ill-defined assemblage of forms, agreeing in the 

 possession of a slimy thallus, varying considerably, 

 however, in its outward shape and mode of develop- 

 ment, most frequently strand-like, but in some cases 

 cushion-shaped and clothed in all cases with filaments 

 of which the primary function is assimilative. Both 

 plurilocular and unilocular sporangia occur, and these 

 also vary in their mode of origin. The unilocular 

 sporangia arise either in the place of the assimilative 

 filaments or as lateral outgrowths of these, while the 

 plurilocular sporangia are produced either in similar 

 fashion or by the transformation of a portion of the 

 assimilative filaments. 



The Thallus. Though there are gaps in our 

 knowledge of the development of a number of the 

 genera, it is probable that most of those having a 

 strand-like growth more or less resemble Chordaria in 

 this respect. It has an axial tissue of parenchymatous 

 character, clothed with assimilative filaments and 

 hairs. Growth in length is effected by the division 

 of the subterminal cells of the thallus, which con- 

 tribute to the growth of the axial tissue on the one 

 hand and to the production of terminal assimilative 

 filaments on the other. These eventually, by the 

 production of new ones and the progressive growth 

 of the thallus, are pushed aside and take the position 

 of lateral filaments. More simple modifications of this 

 mode of development occur in the other genera of 



