by drying, if carefully examined, their tubular ftruflure may be obferved. Ddle- 

 nlus's defcrlption is fb good, that I think it is impoffible to miftake him ; he has 

 publifhed no reprefentation of it, affigning as a reafon that fince its parts elude 

 the fight, it would be rafhnefs to attempt a figure. There is however a rough 

 pencilled fketch among the original drawings in the extenfive library, fo happdy 

 for fcience, belonging to Sir Jofeph Banks, which merely reprefents a number of 

 fibres lying together without any order. 



The growth of this plant is aftonifhingly rapid, fo that I have obferved a very 

 fenfible difference in the length of its filaments in half an hour, and to this, and 

 their extreme minutenefs, which allows the flighted motion of the water, in winch 

 they are examined, to affed them, I attribute the motion obferved by M. Adan- 

 fon and defcribed in an excellent paper in the Hiftoire de T Academie Royale des 

 Sciences for i 7 6 7) page 1S . Here M. Adanfon relates the following difcovery, 

 which, though I have not been fo fortunate as to fee the attual dmfion of the 

 filaments he mentions, feems, from many appearances I have obferved, extremely 

 probable, and highly defervbg of further attention: « Lorfque ces filets font par- 

 venus a leur dernier terme d'accroifement, qui excede rarement trois hgnes, alors 

 le dernier nceud, qui n'a guere qu'une demi-lignede long, s'en fepare et s'alonge; 

 fes deux bouts s'arrondifent, et il devient abfolument femblable a celui dont d 

 s'etoit fepare, et capable d'en produire a fon tour de nouveaux." 



Dr Roth's Conferva velufma feems from his account* of it to refemble the 

 prefent fpecies both in fubftance and mode of growth, but fpecimens from h.m- 

 felf, and his deferring it ' filamentis ramofis' prove them to be different. 



A. C. limofa, natural fize. 



B. Ditto magnified I. 



♦Cat. Bot.I. p. l66- 



