SECT. II. 



CHORDARIJE. 



245 



order, as in the Ulvas. These two organs are for the 

 most part situated on different individuals; in Ecto- 

 carpus pusillus (fig. 29 b) they are on the same. The 

 different forms of fruit carpels are represented magnified 

 in fig. 29. 



The Ectocarpese contain little or no gelatine, whereas 

 the genera of the group Chordarise have soft gelatinous 

 fronds of many forms, either incrustations, convex lumps, 

 or tubers, like the Leathesia so common on our coasts ; 

 small plants as the Mesogloias, which have soft slippery 

 filiform stems beset with myriads of moniliferous worm- 

 like branches; or 

 lastly the Chorda 

 filum, a simple 

 unbranched slimy 

 cylindrical cord, 

 varying from a 

 quarter of an inch 

 to the thickness 

 of a pencil, and 

 from one to twenty 

 or even forty feet 

 in length in deep 

 water. The cord is tubular, divided into chambers 

 by transverse partitions, formed of interlaced vertical 

 and horizontal articulated threads. It tapers at each 

 extremity, and the exterior, which is brown, is clothed 

 with pellucid hairs. Vertical spores are immersed 

 throughout the whole surface of the cord, and Dr. 

 Harvey says that, mixed with these, there are numerous 

 narrow, elliptical, transversely striated cells, which ac- 

 cording to M. Thuret produce zoospores. Each plant 

 rises solitary from its own little disc, but as the Chorda 

 filum is a social plant, vast assemblies of it cover exten- 

 sive areas of sand and mud, and form dense thickets in 

 our northern seas. There are bands of it in the North 



Fig. 29. Fruit of Ectocarpns : a, E. gpliaeroeporns ; 6, 

 E. pusillus ; c, E. f enestratns ; &, E. f asciculatus. 



