Preface. vii 



Director of the United States National Museum, Doctor 

 Charles S. Sargent, Director of the Arnold Arboretum 

 at Jamaica Plains, Mr. C. E. Faxon, of the same institu 

 tion, Honorable Thomas Meehan, of Philadelphia, and 

 W. H. Venable, LL. D., of Cincinnati, have all contrib 

 uted valuable aid. Doctor Goode especially has cour 

 teously furnished all the references to the rare Specchio 

 delle Scienze, and has also verified others; he further 

 has looked over the proofs of part of the bibliographic 

 portion as they came from the printer, and has made 

 numerous valuable suggestions. I desire to make especial 

 mention of the aid afforded by Miss Johanna Peter, of 

 Lexington, who kindly undertook the laborious task of 

 a careful search through the Lexington Library, rich 

 in old Kentucky books and newspaper files, and thus 

 led to the discovery of many useful items. Mr. Alexander 

 Griswold kindly photographed the pages for the plate 

 illustrating the Florula Ludovic iana ; Doctor William 

 T. Durrett did the same with the page for the plate 

 from the Fishes of the River Ohio. Mrs. Asa Gray 

 has courteously allowed the use of the letter to De Can- 

 dolle, from among the letters left by Doctor Asa Gray, 

 which is herein reproduced. To Doctor B. L. Robinson, 

 Curator of the Herbarium at Harvard University, thanks 

 are due for the opportunity to photograph the portrait 



