208 Dr. R. D. Thomson on 



authorities, and not because I believe it to be distinct from 

 the Byssus ; for a very trivial examination was quite suffi- 

 cient to convince me that both plants are mere varieties, or 

 different states of the same species. The only distinction 

 seems to be the darker colour of the filaments, and their 

 more rigid consistence, indicating a more advanced state 

 than the softness of the Byssus. Whether this distinction 

 be accurate or not, however, it seems to have no influence 

 upon their subsequent state, as the filaments of both plants 

 gradually become more moist, collapse, and run together, 

 giving rise to the gelatinous stalactites to which I have 

 already referred. These possess a yellowish brown colour, 

 and a taste like gum Arabic ; their length is from two to 

 three inches, and their diameter from -J to \ inch, tapering 

 gradually from a broader base, which measures about 1| inch 

 across. Some specimens were about 6 inches in length. 

 The substance of which they consisted, exhibited neither an 

 acid nor alkaline re-action, when test paper was exposed to 

 its influence. 



A small portion, when heated in a tube over a spirit lamp, 

 disengaged a great quantity of vapour, and a vegetable 

 odour similar to that produced by the destructive distilla- 

 tion of the woody matter of herbaceous plants. The vapour 

 was condensed, and collected on a watch glass ; it exhibited 

 neither an acid nor alkaline re-action, possessed no taste, 

 and left no residue, when evaporated to dryness. It was, 

 therefore, pure water. A substance resembling dry mem- 

 brane or glue when spread out thinly over a surface and 

 dried, remained after the separation of all the water. When 

 the heat was urged further, smoke began to rise, and con- 

 tinued to augment until nothing remained but a white 

 powder mixed with some carbonaceous matter ; the former 

 dissolved with effervescence completely in pure dilute nitric 

 acid ; the solution afforded a white precipitate with oxalate 

 of ammonia, ana a few flocks fell when caustic ammonia 

 was poured into the solution, indicating the presence of 

 carbonate and phosphate of lime. 



A large portion of the gelatinous mass was boiled for 

 some hours in a flask with a considerable quantity of water; 

 the solid matter was allowed to settle, and the supernatant 

 liquid was withdrawn by a sucker. The liquid thus sepa- 



