Ever truly your friend,
L. AGASSIZ.
The repose of the return voyage, after sixteen months of such uninterrupted work, and of fresh impressions daily crowding upon each other, was most grateful to Agassiz. The summary of this delightful journey may close as it began with a letter to his mother.
AT SEA, July 7, 1866.
DEAR MOTHER,
When you receive this letter we shall be, I hope, at Nahant, where our children and grandchildren are waiting for us. To-morrow we shall stop at Pernambuco, where I shall mail my letter to you by a French steamer.
I leave Brazil with great regret. I have passed nearly sixteen months in the uninterrupted enjoyment of this incomparable tropical nature, and I have learned many things which have enlarged my range of thought, both concerning organized beings and concerning the structure of the earth. I have found traces of glaciers under this burning sky; a proof that our earth has undergone changes of temperature more considerable than even our most advanced glacialists have dared to suggest. Imagine, if you can, floating ice under the equator, such as now exists on the coasts of Greenland, and you will probably have an approximate idea of the aspect of the Atlantic Ocean at that epoch.
It is, however, in the basin of the Amazons especially, that my researches have been crowned with an unexpected success. Spix and Martius, for whose journey I wrote, as you doubtless remember, my first work on fishes, brought back from there some fifty species, and the sum total known now, taking the results of all the travelers who have followed up the inquiry, does not amount to two hundred. I had hoped, in making fishes the special object of my researches, to add perhaps a hundred more. You will understand my surprise when I rapidly obtained five or six hundred, and finally, on leaving Para, brought away nearly two thousand,—that is to say, ten times more than were known when I began my journey.* (* This estimate was made in the field when close comparison of specimens from distant localities was out of the question. The whole collection has never been worked up, and it is possible that the number of new species it contains, though undoubtedly greatly in excess of those previously known from the Amazons, may prove to be less than was at first supposed.—ED.) A great part of this success is due to the unusual facilities granted me by the Brazilian government. . .To the Emperor of Brazil I owe the warmest gratitude. His kindness to me has been beyond all bounds. . .He even made for me, while he was with the army last summer, a collection of fishes from the province of Rio Grande du Sud. This collection would do honor to a professional naturalist. . .
Good-by, dear mother.
With all my heart,