INTRODUCTION. 



FRENCH was the native tongue of Louis Agassiz. 

 His remarkable and admirable mother knew neither 

 English nor German, but wrote French with great 

 purity and choice of expression. As one of the family 

 in Switzerland writes me, " ses lettres sont charmantes, 

 elle ecrivait a merveille." All the great works of 

 Agassiz, on which his reputation as an original natu- 

 ralist is based, are in the French language. The most 

 active part of his life, as regards great discoveries, was 

 spent at Neuchatel, then a small town, where French is 

 the only language spoken. Before he came to America, 

 all his correspondence with English naturalists was in 

 French ; so that it is almost impossible entirely to sup- 

 press this language in writing an accurate and true life 

 of him. Translations, however good, never give an 

 exact idea of what the author means, especially in 

 the case of difficult and delicate observations in natural 

 history. 



After long consideration, I have, therefore, concluded 

 to give what I quote of his correspondence in the origi- 

 nal. All English-speaking naturalists read French now. 

 As the interest of such a book is limited to naturalists 

 and persons whose education leads them to read and 



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