[90]. It is but fitting that I should express here my thanks to Captain Faria for the courteous manner in which he accomplished the task assigned him by the government. He was not only a most hospitable host on board his vessel, but he allowed me to encumber his deck with all kinds of scientific apparatus, and gave me very efficient assistance in collecting.—L. A.
[91].
Pará, February 23, 1866.
Sire:—On arriving at Pará in the beginning of this month, I had the pleasure to find your Majesty’s kind letter, which had been awaiting me for several days. I ought to have acknowledged it immediately, but I was not in a condition to do so, being overcome by fatigue. It is only during the last two or three days that I begin once more to occupy myself as usual. I confess that nothing but the presentiment of regrets which would have pursued me to the end of my days has prevented me from returning directly to the United States. Even now I find it difficult to take up the most simple occupations. And yet I am not ill; I am only exhausted by incessant work, and by the contemplation, each day more vivid and impressive, of the grandeur and beauty of this tropical nature. I need to look for a time upon the sombre and monotonous aspect of a pine forest.
How good you are, Sire, to think of me in the midst of the vital affairs which absorb your attention, and how considerate are your acts! The New Year’s present you announce enchants me.[[93]] The prospect of being able to add some comparisons of the fishes from the basin of the Uruguay to such as I have already made between the Amazonian species and those of the rivers on the eastern coast of Brazil has a special attraction for me. It will be the first step towards a knowledge of the types of the temperate zone in South America. I wait with increasing impatience for the moment when I shall be able to examine them. In the mean while allow me to give you a rapid sketch of the results thus far obtained in my voyage on the Amazons.
I will not return to the surprising variety of species of fishes contained in this basin, though it is very difficult for me to familiarize myself with the idea that the Amazons nourishes nearly twice as many species as the Mediterranean, and a larger number than the Atlantic, taken from one pole to the other. I can no longer say, however, with precision, what is the exact number of species which we have procured from the Amazons, because, on retracing my steps as I descended the great river, I have seen fishes about to lay their eggs which I had seen at first under other conditions, and vice versa; and without consulting the collections made six months ago, and which are not now accessible to me, it is often impossible for me to determine from memory whether they are the same species, or different ones which escaped my observation in my first examination. However, I estimate the total number of species which I actually possess at eighteen hundred, and it may be two thousand.[[94]] But it is not only the number of species which will astonish naturalists; the fact that they are for the most part circumscribed within definite limits is still more surprising, and cannot but have a direct influence on the ideas now prevalent respecting the origin of living beings. That in a river like the Mississippi, which from the north to the south passes successively through cold, temperate, and warm zones,—whose waters flow sometimes over one geological formation, sometimes over another, and across plains covered at the north by an almost arctic vegetation, and at the south by a sub-tropical flora,—that in such a basin aquatic animals of different species should be met at various points of its course is easily understood by those who are accustomed to consider general conditions of existence, and of climate especially, as the first cause of the difference between animals and plants inhabiting separate localities. But that from Tabatinga to Pará, in a river where the waters differ neither in temperature nor in the nature of their bed, nor in the vegetation along their borders,—that under such circumstances there should be met, from distance to distance, assemblages of fishes completely distinct from each other, is indeed astonishing. I would even say that henceforth this distribution, which may be verified by any one who cares to take the trouble, must throw much doubt on the opinion which attributes the diversity of living beings to local influences. Another side of this subject, still more curious perhaps, is the intensity with which life is manifested in these waters. All the rivers of Europe united, from the Tagus to the Volga, do not nourish one hundred and fifty species of fresh-water fishes; and yet, in a little lake near Manaos, called Lago Hyanuary, the surface of which covers hardly four or five hundred square yards, we have discovered more than two hundred distinct species, the greater part of which have not been observed elsewhere. What a contrast!
The study of the mixture of human races in this region has also occupied me much, and I have procured numerous photographs of all the types which I have been able to observe. The principal result at which I have arrived is, that the races bear themselves towards each other as do distinct species; that is to say, that the hybrids, which spring from the crossing of men of different races, are always a mixture of the two primitive types, and never the simple reproduction of the characters of one or the other progenitor, as is the case among the races of domestic animals.
I will say nothing of my other collections, which have been made for the most part by my young companions, rather with a view to enrich our Museum than to solve scientific questions. But I cannot allow this occasion to pass without expressing my lively gratitude for all the facilities, in my explorations, which I have owed to the kindness of your Majesty. From the President to the most humble employés of the provinces I have visited, all have competed with each other to render my work more easy; and the steamship company of the Amazons has shown an extreme liberality towards me. Finally, Sire, the generosity with which you have placed at my disposition a vessel of war has allowed me to make collections which, with less ample and rapid means of transport, must have remained utterly inaccessible to me. Permit me to add, that, of all the favors with which your Majesty has crowned this voyage, the most precious has been the presence of Major Coutinho, whose familiarity with all which concerns the Amazons has been an inexhaustible source of important information and of useful directions; by means of which the loss of time in unremunerative excursions has been avoided. His co-operation during this journey has been most laborious; he has applied himself to zoölogy as if the physical sciences had not hitherto been the special object of his study, while at the same time he has made numerous thermometric, barometric, and astronomical observations, which will furnish important additions to what is already known concerning the meteorology and topography of these provinces. We have, for instance, been the first to carry the barometer into the midst of the hills of Almeyrim, of Monte Alégre and Ereré, and to measure their highest summits. The study of the formation of the valley of the Amazons has naturally occupied me, though in a secondary degree, from the first day of my arrival.[[95]]
[92]. Humboldt’s Personal Narrative, Bohn’s Scientific Library, Vol. II. Chap. XX. p. 267.
[93]. The Emperor had written to Mr. Agassiz that, during the time when he took command of the Brazilian army on the Rio Grande, he had caused collections of fishes to be made for him from several of the southern rivers.