received opinion. He found that the fmall quantity of ammonia contained in 

 Conferva is combined with pyromucous acid, which is the cafe in many 

 vegetables : that they do not give out muriate of foda, as Meffrs. Chantrons 

 and Lacroix have affirmed, but muriate and carbonate of potafh, and if they 

 had contained foda, this is only what occurs in feveral other plants. He confiders 

 the quantity of aibes they afford as a ftill further proof, and upon the whole 

 entertains no doubt that their fubftance is truly vegetable.* M. Decandolle has 

 alfo, in my opinion, fuccefsfully controvered M. Chantrons' theory ; and I there- 

 fore need only add, that I have never difcovered an appearance in any of the 

 Alga; which occafioned the lead fufpicion in my mind that they are not true and 

 perfect vegetables. 



With regard to the prefent arrangement of the fubmerfed Alg/c, I have little 

 more to add than that nothing can more fully evince our ignorance refpecting 

 them, or fhew how imperfectly they have been hitherto ftudied, than the cir- 

 cumftance of fo many difcordant fpecies being placed together, as thofe of which 

 the prefent genera are compofed. It may probably be expected, that in a work of 

 this kind I fhould attempt fome better arrangement, but, though fatisfied of the 

 neceffity of fuch a talk, I can only lament my inadequacy to the execution of 

 it : the time is not yet arrived ; fufficient materials are not yet collected ; and it 

 fhould be deferred not only till the Conferva, but alfo till the Fuel, Ulvt, and 

 Tremella are better known, as well with regard to their fructification as to the 

 number of their fpecies ; for many are ftill frequently difcovered, differing 

 effentially in their modes of propagation from thofe before known. Crude and 

 undigefted attempts at reformation ferve in Botany, as in other matters, to per- 

 plex rather than to enlighten, and I will therefore add nothing further on this 

 fubject, than that I fully agree with my friend Mr. Turner, that, previoufly to 

 any permanent fyftem being eftablifhed, it wiil be neceffary to reduce the prefent 

 genera into one mafs, and proceed in nearly the fame manner as if nothing had 

 been done before. 



* Journal de Phyfiquc, liv. p. 427. 



