G6 THOKE^. 



shorter than the filaments which give origin to them. The 

 first are always simple, the latter are covered with new 

 shoots, still shorter, up to near the extremities, these are 

 usually simple, so that the last branches are constantly 

 naked. 



" The whole plant is covered with a fine and mucous down, 

 about half a line long or more. This down gives to the 

 branches. the appearance of little cylindrical stalks of the 

 size of a crow-quill. It is composed of simj^le " (rarely 

 branched) " threads in the form of cilia, in which the joints 

 are not apparent with a simple magnifying glass, but in 

 which they are distinguished when they are submitted to 

 a very strong lens. 



'^ The branches of Thorea ramosissima are often many feet 

 in length, and float gently in the water, whose course they 

 follow. Their colour is an obscure and deep green. They 

 assume very frequently on paper a very elegant scarlet tint. 

 When they are macerated in pure water, they soon acquire 

 the same tint, and they communicate it to every thing wliich 

 surrounds them. Pieces of flax, cotton, and silk contained 

 in the same vessels become dyed in a manner often very 

 intense. This circumstance has made me presume that some 

 use in the arts might be made for the fecula of Thorea ra- 

 mosissima^'' 



After detailing numerous chemical experiments, M. Bory 

 de St. Vincent concludes his description of the species with 

 the following remarks : — '^ As to the use which might be 

 made of the fecula, that is easy ; painters have found its tint 

 more soft and more brilliant than that of violets obtained by 

 other processes; but I doubt whether this beautiful colour 

 would be very durable, by reason of the action which oxygen 

 necessarily exercises upon it, as one of the experiments we 

 have related shows." 



The capsules, as seen in fig. 4. of plate xvi., which figure 

 is taken from Kiitzing's " Phycologia Generalis," would ap- 

 pear to bear a close resemblance to those of TrentcpSilia 

 pulchella, being, as in that species, small, pyriform, corymbose, 

 and subinvolucrate ; the secondary branches are occasionally. 



