and Plants confounded with them. 207 



Link never could observe this. All these species, ac- 

 cording to him, possess cavities which proceed far into the 

 branches, and possess a structure very analogous to Osteo- 

 colla or calcareous tuff, which covers junci and other plants 

 in ponds. In his opinion, tbe Nullipores are nothing else 

 than a similar calcareous deposit which are formed round 

 marine plants. 



Article IV. 



On a Vegeto- Calcareous Hydrate, produced from Byssus 

 Floccosa. By Robert D. Thomson, M. D. 



While lately viewing the cellars of Henry Gill and Co., 

 in Mark Lane, my attention was attracted by observing a 

 number of gelatinous looking stalactites hanging from the 

 roof. The intervals between their bases were occupied by 

 large tufts of Byssus floccosa and Racodium cellare, which 

 in some instances appeared to be intermixed with them, and 

 to have assumed that black and soft state, so remarkable in 

 these curious plants ; a form in which they have been re- 

 commended as styptics. The Byssus floccosa is a very com- 

 mon inhabitant of cellars, and is characterized, when in the 

 state of maturity, by its beautiful snow-white tufts, arranged 

 in an orbicular form ; the filaments or elements of the tuft 

 being close, simple, and parallel. When this plant is situ- 

 ated on a roof, timber, or cask, it assumes a pendent form, 

 and, at first sight, has a close similarity to cotton. When 

 pressed between sheets of blotting paper, the filaments are 

 closely compressed and stick to the paper ; the plant then 

 assuming the appearance of one of the fleshy fungi after 

 being subjected to pressure. The filaments cross each other, 

 and from their glutinous nature are very liable to adhere 

 to each other, and to any object with which they may hap- 

 pen to come in contact. When examined by the microscope, 

 they appear to be fistulose and jointed, or at least, the in- 

 ternal vacancy is not cylindrical, but contracted and dilated 

 at irregular and distant intervals. 



I have noticed the Racodium cellare as occurring inter- 

 mixed with the Byssus because I observed several filaments 

 which answered the description given by the best botanical 



