第1章 AN APPRECIATIONBY CHARLES DARWIN(1)
Author of "The Origin of Species," etc.
From Natural History Review, vol.iii.1863.
IN April, 1848, the author of the present volume left England in company with Mr.A.R.Wallace--"who has since acquired wide fame in connection with the Darwinian theory of Natural Selection"--on a joint expedition up the river Amazons, for the purpose of investigating the Natural History of the vast wood-region traversed by that mighty river and its numerous tributaries.Mr.
Wallace returned to England after four years' stay, and was, we believe, unlucky enough to lose the greater part of his collections by the shipwreck of the vessel in which he had transmitted them to London.Mr.Bates prolonged his residence in the Amazon valley seven years after Mr.Wallace's departure, and did not revisit his native country again until 1859.Mr.Bates was also more fortunate than his companion in bringing his gathered treasures home to England in safety.So great, indeed, was the mass of specimens accumulated by Mr.Bates during his eleven years' researches, that upon the working out of his collection, which has been accomplished (or is now in course of being accomplished) by different scientific naturalists in this country, it has been ascertained that representatives of no less than 14,712 species are amongst them, of which about 8000 were previously unknown to science.It may be remarked that by far the greater portion of these species, namely, about 14,000, belong to the class of Insects--to the study of which Mr.Bates principally devoted his attention--being, as is well known, himself recognised as no mean authority as regards this class of organic beings.In his present volume, however, Mr.Bates does not confine himself to his entomological discoveries, nor to any other branch of Natural History, but supplies a general outline of his adventures during his journeyings up and down the mighty river, and a variety of information concerning every object of interest, whether physical or political, that he met with by the way.
Mr.Bates landed at Para in May, 1848.His first part is entirely taken up with an account of the Lower Amazons--that is, the river from its sources up to the city of Manaos or Barra do Rio Negro, where it is joined by the large northern confluent of that name--and with a narrative of his residence at Para and his various excursions in the neighbourhood of that city.The large collection made by Mr.Bates of the animal productions of Para enabled him to arrive at the following conclusions regarding the relations of the Fauna of the south side of the Amazonian delta with those of other regions.
"It is generally allowed that Guiana and Brazil, to the north and south of the Para district, form two distinct provinces, as regards their animal and vegetable inhabitants.By this it means that the two regions have a very large number of forms peculiar to themselves, and which are supposed not to have been derived from other quarters during modern geological times.Each may be considered as a centre of distribution in the latest process of dissemination of species over the surface of tropical America.
Para lies midway between the two centres, each of which has a nucleus of elevated table-land, whilst the intermediate river-valley forms a wide extent of low-lying country.It is, therefore, interesting to ascertain from which the latter received its population, or whether it contains so large a number of endemic species as would warrant the conclusion that it is itself an independent province.To assist in deciding such questions as these, we must compare closely the species found in the district with those of the other contiguous regions, and endeavour to ascertain whether they are identical, or only slightly modified, or whether they are highly peculiar.
"Von Martius when he visited this part of Brazil forty years ago, coming from the south, was much struck with the dissimilarity of the animal and vegetable productions to those of other parts of Brazil.In fact the Fauna of Para, and the lower part of the Amazons has no close relationship with that of Brazil proper; but it has a very great affinity with that of the coast region of Guiana, from Cayenne to Demerara.If we may judge from the results afforded by the study of certain families of insects, no peculiar Brazilian forms are found in the Para district; whilst more than one-half of the total number are essentially Guiana species, being found nowhere else but in Guiana and Amazonia.