O PREAMBLE. 



modern labors similar to mine, without finding 

 the same accuracy and perspicuity of Generic 

 reform. Wiiile it is with tlie utmost difficulty I 

 can obtain even for rnoneij some late works of 

 similar tendency, although 1 try to correspond 

 direct with the Authors. 



Therefore I distinctly state here again, that 

 my feelings being of the most liberal and friend- 

 ly kind for all Botanists and Naturalists, all over 

 the Earth, if my labors ever interfere with 

 theirs it must be accidentaly and unknowingly, 

 either because my CJenera were those establish- 

 ed by me between 1806 and 1815, or because I 

 have not obtained yet their works, although 

 willing to buy them or exchange them with 

 mine, unless they be too costly like Audubon or 

 Jacquin — I hereby call publicly upon all synop- 

 tical and improving Botanists (and even Zoolo- 

 gists and Oryctologists) such as Agardh, De- 

 candole, Endlicker, Schreber, Sprengel, Fries, 

 R. Brown, Lindley, Hooker, Don, Sweet, Ar- 

 nott, Bentham, Nees, Fischer, Link, Tenore, 

 Ledebour, Blume, Martins, St. Hilaire, Bory, 

 &c . . , with others unknowu to me by name as 

 yet, to send me their works in exchange of mine 

 and also to exchange specimens. I have been 

 permanently established in Philadelphia again 

 since 1826, and shall' probably ever continue 

 here, although I may become connected v^^ith 

 various literary institutions, particularly the 

 Central University of Illinois of which I am 

 one of the founders. Books sent me for the 

 University will be free of duties, and equaly re- 

 ceived in exchange. 



When I have accumulated all the latest Ma- 

 terials or Genera, and the great work of De- 

 candole is completed, I may then revise the 



