A NATURALIST’S VOYAGE
ROUND THE WORLD
First Edition May 1860
Second Edition May 1870
Third Edition February 1872
Fourth Edition July 1874
Fifth Edition March 1876
Sixth Edition January 1879
Seventh Edition May 1882
Eighth Edition February 1884
Ninth Edition August 1886
Tenth Edition January 1888
Eleventh Edition January 1890
Reprinted June 1913
[Illustration: H.M.S. BEAGLE IN STRAITS OF MAGELLAN. MT SARMIENTO IN
THE DISTANCE.]
Journal of Researches
into the
Natural History & Geology
of the
countries visited during the voyage
round the world of H.M.S. _Beagle_
under the command of Captain Fitz Roy, R.N.
By Charles Darwin, M.A., F.R.S.
AUTHOR OF ‘ORIGIN OF SPECIES,’ ETC.
[Illustration]
A new edition with illustrations by R. T. Pritchett
of places visited and objects described.
LONDON
JOHN MURRAY, ALBEMARLE STREET
1913.
TO
CHARLES LYELL, ESQ., F.R.S.
This second edition is dedicated with grateful pleasure, as an
acknowledgment that the chief part of whatever scientific merit this
journal and the other works of the author may possess, has been derived
from studying the well-known and admirable
PRINCIPLES OF GEOLOGY.
PREFATORY NOTICE TO THE ILLUSTRATED EDITION.
This work was described, on its first appearance, by a writer in the
_Quarterly Review_ as “One of the most interesting narratives of
voyaging that it has fallen to our lot to take up, and one which must
always occupy a distinguished place in the history of scientific
navigation.”
This prophecy has been amply verified by experience; the extraordinary
minuteness and accuracy of Mr. Darwin’s observations, combined with the
charm and simplicity of his descriptions, have ensured the popularity
of this book with all classes of readers—and that popularity has even
increased in recent years. No attempt, however, has hitherto been made
to produce an illustrated edition of this valuable work: numberless
places and objects are mentioned and described, but the difficulty of
obtaining authentic and original representations of them drawn for the
purpose has never been overcome until now.
Most of the views given in this work are from sketches made on the spot
by Mr. Pritchett, with Mr. Darwin’s book by his side. Some few of the
others are taken from engravings which Mr. Darwin had himself selected
for their interest as illustrating his voyage, and which have been
kindly lent by his son.
Mr. Pritchett’s name is well known in connection with the voyages of
the _Sunbeam_ and _Wanderer_, and it is believed that the
illustrations, which have been chosen and verified with the utmost care
and pains, will greatly add to the value and interest of the “VOYAGE OF
A NATURALIST.”
JOHN MURRAY.
_December_ 1889.
AUTHOR’S PREFACE.
I have stated in the preface to the first Edition of this work, and in
the _Zoology of the Voyage of the Beagle_, that it was in consequence
of a wish expressed by Captain Fitz Roy, of having some scientific
person on board, accompanied by an offer from him of giving up part of
his own accommodations, that I volunteered my services, which received,
through the kindness of the hydrographer, Captain Beaufort, the
sanction of the Lords of the Admiralty. As I feel that the
opportunities which I enjoyed of studying the Natural History of the
different countries we visited have been wholly due to Captain Fitz
Roy, I hope I may here be permitted to repeat my expression of
gratitude to him; and to add that, during the five years we were
together, I received from him the most cordial friendship and steady
assistance. Both to Captain Fitz Roy and to all the Officers of the
_Beagle_[1] I shall ever feel most thankful for the undeviating
kindness with which I was treated during our long voyage.
[1] I must take this opportunity of returning my sincere thanks to Mr.
Bynoe, the surgeon of the _Beagle_, for his very kind attention to me
when I was ill at Valparaiso.
This volume contains, in the form of a Journal, a history of our
voyage, and a sketch of those observations in Natural History and
Geology, which I think will possess some interest for the general
reader. I have in this edition largely condensed and corrected some
parts, and have added a little to others, in order to render the volume
more fitted for popular reading; but I trust that naturalists will
remember that they must refer for details to the larger publications
which comprise the scientific results of the Expedition. The _Zoology
of the Voyage of the Beagle_ includes an account of the Fossil
Mammalia, by Professor Owen; of the Living Mammalia, by Mr. Waterhouse;
of the Birds, by Mr. Gould; of the Fish, by the Reverend L. Jenyns; and
of the Reptiles, by Mr. Bell. I have appended to the descriptions of
each species an account of its habits and range. These works, which I
owe to the high talents and disinterested zeal of the above
distinguished authors, could not have been undertaken had it not been
for the liberality of the Lords Commissioners of Her Majesty’s
Treasury, who, through the representation of the Right Honourable the
Chancellor of the Exchequer, have been pleased to grant a sum of one
thousand pounds towards defraying part of the expenses of publication.
I have myself published separate volumes on the _Structure and
Distribution of Coral Reefs_; on the _ Volcanic Islands visited during
the Voyage of the Beagle_; and on the _Geology of South America._ The
sixth volume of the _ Geological Transactions_ contains two papers of
mine on the Erratic Boulders and Volcanic Phenomena of South America.
Messrs. Waterhouse, Walker, Newman, and White, have published several
able papers on the Insects which were collected, and I trust that many
others will hereafter follow. The plants from the southern parts of
America will be given by Dr. J. Hooker, in his great work on the Botany
of the Southern Hemisphere. The Flora of the Galapagos Archipelago is
the subject of a separate memoir by him, in the _ Linnean
Transactions._ The Reverend Professor Henslow has published a list of
the plants collected by me at the Keeling Islands; and the Reverend J.
M. Berkeley has described my cryptogamic plants.
I shall have the pleasure of acknowledging the great assistance which I
have received from several other naturalists in the course of this and
my other works; but I must be here allowed to return my most sincere
thanks to the Reverend Professor Henslow, who, when I was an
undergraduate at Cambridge, was one chief means of giving me a taste
for Natural History,—who, during my absence, took charge of the
collections I sent home, and by his correspondence directed my
endeavours,—and who, since my return, has constantly rendered me every
assistance which the kindest friend could offer.
DOWN, BROMLEY, KENT,
_June_ 1845.
CONTENTS
CHAPTER I
Porto Praya — Ribeira Grande — Atmospheric Dust with Infusoria — Habits
of a Sea-slug and Cuttle-fish — St. Paul’s Rocks, non-volcanic —
Singular Incrustations — Insects the first Colonists of Islands —
Fernando Noronha — Bahia — Burnished Rocks — Habits of a Diodon —
Pelagic Confervæ and Infusoria — Causes of discoloured Sea.
CHAPTER II
Rio de Janeiro — Excursion north of Cape Frio — Great Evaporation —
Slavery — Botofogo Bay — Terrestrial Planariæ — Clouds on the
Corcovado — Heavy Rain — Musical Frogs — Phosphorescent insects —
Elater, springing powers of — Blue Haze — Noise made by a Butterfly —
Entomology — Ants — Wasp killing a Spider — Parasitical Spider —
Artifices of an Epeira — Gregarious Spider — Spider with an
unsymmetrical web.
CHAPTER III
Monte Video — Maldonado — Excursion to R. Polanco — Lazo and Bolas —
Partridges — Absence of trees — Deer — Capybara, or River Hog —
Tucutuco — Molothrus, cuckoo-like habits — Tyrant-flycatcher —
Mocking-bird — Carrion Hawks — Tubes formed by lightning — House
struck.
CHAPTER IV
Rio Negro — Estancias attacked by the Indians — Salt-Lakes — Flamingoes
— R. Negro to R. Colorado — Sacred Tree — Patagonian Hare — Indian
Families — General Rosas — Proceed to Bahia Blanca — Sand Dunes — Negro
Lieutenant — Bahia Blanca — Saline incrustations — Punta Alta —
Zorillo.
CHAPTER V
Bahia Blanca — Geology — Numerous gigantic extinct Quadrupeds — Recent
Extinction — Longevity of Species — Large Animals do not require a
luxuriant vegetation — Southern Africa — Siberian Fossils — Two Species
of Ostrich — Habits of Oven-bird — Armadilloes — Venomous Snake, Toad,
Lizard — Hybernation of Animals — Habits of Sea-Pen — Indian Wars and
Massacres — Arrowhead — Antiquarian Relic.
CHAPTER VI
Set out for Buenos Ayres — Rio Sauce — Sierra Ventana — Third Posta —
Driving Horses — Bolas — Partridges and Foxes — Features of the country
— Long-legged Plover — Teru-tero — Hail-storm — Natural enclosures in
the Sierra Tapalguen — Flesh of Puma — Meat Diet — Guardia del Monte —
Effects of cattle on the Vegetation — Cardoon — Buenos Ayres — Corral
where cattle are slaughtered.
CHAPTER VII
Excursion to St. Fé — Thistle Beds — Habits of the Bizcacha — Little
Owl — Saline streams — Level plains — Mastodon — St. Fé — Change in
landscape — Geology — Tooth of extinct Horse — Relation of the Fossil
and recent Quadrupeds of North and South America — Effects of a great
drought — Parana — Habits of the Jaguar — Scissor-beak — Kingfisher,
Parrot, and Scissor-tail — Revolution — Buenos Ayres — State of
Government.
CHAPTER VIII
Excursion to Colonia del Sacramiento — Value of an Estancia — Cattle,
how counted — Singular breed of Oxen — Perforated pebbles —
Shepherd-dogs — Horses broken-in, Gauchos riding — Character of
Inhabitants — Rio Plata — Flocks of Butterflies — Aëronaut Spiders —
Phosphorescence of the Sea — Port Desire — Guanaco — Port St. Julian —
Geology of Patagonia — Fossil gigantic Animal — Types of Organisation
constant — Change in the Zoology of America — Causes of Extinction.
CHAPTER IX
Santa Cruz — Expedition up the River — Indians — Immense streams of
basaltic lava — Fragments not transported by the river — Excavation of
the valley — Condor, habits of — Cordillera — Erratic boulders of great
size — Indian relics — Return to the ship — Falkland Islands — Wild
horses, cattle, rabbits — Wolf-like fox — Fire made of bones — Manner
of hunting wild cattle — Geology — Streams of stones — Scenes of
violence — Penguin — Geese — Eggs of Doris — Compound animals.
CHAPTER X
Tierra del Fuego, first arrival — Good Success Bay — An account of the
Fuegians on board — Interview with the savages — Scenery of the forests
— Cape Horn — Wigwam Cove — Miserable condition of the savages —
Famines — Cannibals — Matricide — Religious feelings — Great Gale —
Beagle Channel — Ponsonby Sound — Build wigwams and settle the Fuegians
— Bifurcation of the Beagle Channel — Glaciers — Return to the Ship —
Second visit in the Ship to the Settlement — Equality of condition
amongst the natives.
CHAPTER XI
Strait of Magellan — Port Famine — Ascent of Mount Tarn — Forests —
Edible fungus — Zoology — Great Seaweed — Leave Tierra del Fuego —
Climate — Fruit-trees and productions of the southern coasts — Height
of snow-line on the Cordillera — Descent of glaciers to the sea —
Icebergs formed — Transportal of boulders — Climate and productions of
the Antarctic Islands — Preservation of frozen carcasses —
Recapitulation.
CHAPTER XII
Valparaiso — Excursion to the foot of the Andes — Structure of the land
— Ascend the Bell of Quillota — Shattered masses of greenstone —
Immense valleys — Mines — State of miners — Santiago — Hot-baths of
Cauquenes — Gold-mines — Grinding-mills — Perforated stones — Habits of
the Puma — El Turco and Tapacolo — Humming-birds.
CHAPTER XIII
Chiloe — General aspect — Boat excursion — Native Indians — Castro —
Tame fox — Ascend San Pedro — Chonos Archipelago — Peninsula of Tres
Montes — Granitic range — Boat-wrecked sailors — Low’s Harbour — Wild
potato — Formation of peat — Myopotamus, otter and mice — Cheucau and
Barking-bird — Opetiorhynchus — Singular character of ornithology —
Petrels.
CHAPTER XIV
San Carlos, Chiloe — Osorno in eruption, contemporaneously with
Aconcagua and Coseguina — Ride to Cucao — Impenetrable forests —
Valdivia — Indians — Earthquake — Concepcion — Great earthquake — Rocks
fissured — Appearance of the former towns — The sea black and boiling —
Direction of the vibrations — Stones twisted round — Great Wave —
Permanent Elevation of the land — Area of volcanic phenomena — The
connection between the elevatory and eruptive forces — Cause of
earthquakes — Slow elevation of mountain-chains.
CHAPTER XV
Valparaiso — Portillo Pass — Sagacity of mules — Mountain-torrents —
Mines, how discovered — Proofs of the gradual elevation of the
Cordillera — Effect of snow on rocks — Geological structure of the two
main ranges, their distinct origin and upheaval — Great subsidence —
Red snow — Winds — Pinnacles of snow — Dry and clear atmosphere —
Electricity — Pampas — Zoology of the opposite sides of the Andes —
Locusts — Great Bugs — Mendoza — Uspallata Pass — Silicified trees
buried as they grew — Incas Bridge — Badness of the passes exaggerated
— Cumbre — Casuchas — Valparaiso.
CHAPTER XVI
Coast-road to Coquimbo — Great loads carried by the miners — Coquimbo —
Earthquake — Step-formed terraces — Absence of recent deposits —
Contemporaneousness of the Tertiary formations — Excursion up the
valley — Road to Guasco — Deserts — Valley of Copiapó — Rain and
Earthquakes — Hydrophobia — The Despoblado — Indian ruins — Probable
change of climate — River-bed arched by an earthquake — Cold gales of
wind — Noises from a hill — Iquique — Salt alluvium — Nitrate of soda —
Lima — Unhealthy country — Ruins of Callao, overthrown by an earthquake
— Recent subsidence — Elevated shells on San Lorenzo, their
decomposition — Plain with embedded shells and fragments of pottery —
Antiquity of the Indian Race.
CHAPTER XVII
Galapagos Archipelago — The whole group volcanic — Number of craters —
Leafless bushes — Colony at Charles Island — James Island — Salt-lake
in crater — Natural history of the group — Ornithology, curious finches
— Reptiles — Great tortoises, habits of — Marine lizard, feeds on
seaweed — Terrestrial lizard, burrowing habits, herbivorous —
Importance of reptiles in the Archipelago — Fish, shells, insects —
Botany — American type of organisation — Differences in the species or
races on different islands — Tameness of the birds — Fear of man an
acquired instinct.
CHAPTER XVIII
Pass through the Low Archipelago — Tahiti — Aspect — Vegetation on the
mountains — View of Eimeo — Excursion into the interior — Profound
ravines — Succession of waterfalls — Number of wild useful plants —
Temperance of the inhabitants — Their moral state — Parliament convened
— New Zealand — Bay of Islands — Hippahs — Excursion to Waimate —
Missionary establishment — English weeds now run wild — Waiomio —
Funeral of a New Zealand woman — Sail for Australia.
CHAPTER XIX
Sydney — Excursion to Bathurst — Aspect of the woods — Party of natives
— Gradual extinction of the aborigines — Infection generated by
associated men in health — Blue Mountains — View of the grand gulf-like
valleys — Their origin and formation — Bathurst, general civility of
the lower orders — State of Society — Van Diemen’s Land — Hobart Town —
Aborigines all banished — Mount Wellington — King George’s Sound —
Cheerless aspect of the country — Bald Head, calcareous casts of
branches of trees — Party of natives — Leave Australia.
CHAPTER XX
Keeling Island — Singular appearance — Scanty Flora — Transport of
seeds — Birds and insects — Ebbing and flowing springs — Fields of dead
coral — Stones transported in the roots of trees — Great crab —
Stinging corals — Coral-eating fish — Coral formations — Lagoon islands
or atolls — Depth at which reef-building corals can live — Vast areas
interspersed with low coral islands — Subsidence of their foundations —
Barrier-reefs — Fringing-reefs — Conversion of fringing-reefs into
barrier-reefs, and into atolls — Evidence of changes in level —
Breaches in barrier-reefs — Maldiva atolls, their peculiar structure —
Dead and submerged reefs — Areas of subsidence and elevation —
Distribution of volcanoes — Subsidence slow and vast in amount.
CHAPTER XXI
Mauritius, beautiful appearance of — Great crateriform ring of
mountains — Hindoos — St. Helena — History of the changes in the
vegetation — Cause of the extinction of land-shells — Ascension —
Variation in the imported rats — Volcanic bombs — Beds of infusoria —
Bahia, Brazil — Splendour of tropical scenery — Pernambuco — Singular
reefs — Slavery — Return to England — Retrospect on our voyage.
List of Illustrations
Index
[Illustration]
[Illustration]
JOURNAL
Chapter I
Porto Praya—Ribeira Grande—Atmospheric Dust with Infusoria—Habits of a
Sea-slug and Cuttle-fish—St. Paul’s Rocks, non-volcanic—Singular
Incrustations—Insects the first Colonists of Islands—Fernando
Noronha—Bahia—Burnished Rocks—Habits of a Diodon—Pelagic Confervæ and
Infusoria—Causes of discoloured Sea.
ST. JAGO—CAPE DE VERD ISLANDS
After having been twice driven back by heavy south-western gales, Her
Majesty’s ship _Beagle_, a ten-gun brig, under the command of Captain
Fitz Roy, R.N., sailed from Devonport on the 27th of December, 1831.
The object of the expedition was to complete the survey of Patagonia
and Tierra del Fuego, commenced under Captain King in 1826 to 1830—to
survey the shores of Chile, Peru, and of some islands in the
Pacific—and to carry a chain of chronometrical measurements round the
World. On the 6th of January we reached Teneriffe, but were prevented
landing, by fears of our bringing the cholera: the next morning we saw
the sun rise behind the rugged outline of the Grand Canary Island, and
suddenly illumine the Peak of
Teneriffe, whilst the lower parts were veiled in fleecy clouds. This
was the first of many delightful days never to be forgotten. On the
16th of January 1832 we anchored at Porto Praya, in St. Jago, the chief
island of the Cape de Verd archipelago.
The neighbourhood of Porto Praya, viewed from the sea, wears a desolate
aspect. The volcanic fires of a past age, and the scorching heat of a
tropical sun, have in most places rendered the soil unfit for
vegetation. The country rises in successive steps of table-land,
interspersed with some truncate conical hills, and the horizon is
bounded by an irregular chain of more lofty mountains. The scene, as
beheld through the hazy atmosphere of this climate, is one of great
interest; if, indeed, a person, fresh from sea, and who has just
walked, for the first time, in a grove of cocoa-nut trees, can be a
judge of anything but his own happiness. The island would generally be
considered as very uninteresting, but to any one accustomed only to an
English landscape, the novel aspect of an utterly sterile land
possesses a grandeur which more vegetation might spoil. A single green
leaf can scarcely be discovered over wide tracts of the lava plains;
yet flocks of goats, together with a few cows, contrive to exist. It
rains very seldom, but during a short portion of the year heavy
torrents fall, and immediately afterwards a light vegetation springs
out of every crevice. This soon withers; and upon such naturally formed
hay the animals live. It had not now rained for an entire year. When
the island was discovered, the immediate neighbourhood of Porto Praya
was clothed with trees,[1] the reckless destruction of which has caused
here, as at St. Helena, and at some of the Canary islands, almost
entire sterility. The broad, flat-bottomed valleys, many of which serve
during a few days only in the season as watercourses, are clothed with
thickets of leafless bushes. Few living creatures inhabit these
valleys. The commonest bird is a kingfisher (Dacelo Iagoensis), which
tamely sits on the branches of the castor-oil plant, and thence darts
on grasshoppers and lizards. It is brightly coloured, but not so
beautiful as the European species: in its flight, manners, and place of
habitation, which is generally in the driest valley, there is also a
wide difference.
[1] I state this on the authority of Dr. E. Dieffenbach, in his German
translation of the first edition of this Journal.
One day, two of the officers and myself rode to Ribeira Grande, a
village a few miles eastward of Porto Praya. Until we reached the
valley of St. Martin, the country presented its usual dull brown
appearance; but here, a very small rill of water produces a most
refreshing margin of luxuriant vegetation. In the course of an hour we
arrived at Ribeira Grande, and were surprised at the sight of a large
ruined fort and cathedral. This little town, before its harbour was
filled up, was the principal place in the island: it now presents a
melancholy, but very picturesque appearance. Having procured a black
Padre for a guide, and a Spaniard who had served in the Peninsular war
as an interpreter, we visited a collection of buildings, of which an
ancient church formed the principal part. It is here the governors and
captain-generals of the islands have been buried. Some of the
tombstones recorded dates of the sixteenth century.[2] The heraldic
ornaments were the only things in this retired place that reminded us
of Europe. The church or chapel formed one side of a quadrangle, in the
middle of which a large clump of bananas were growing. On another side
was a hospital, containing about a dozen miserable-looking inmates.
[2] The Cape de Verd Islands were discovered in 1449. There was a
tombstone of a bishop with the date of 1571; and a crest of a hand and
dagger, dated 1497.
We returned to the Vênda to eat our dinners. A considerable number of
men, women, and children, all as black as jet, collected to watch us.
Our companions were extremely merry; and everything we said or did was
followed by their hearty laughter. Before leaving the town we visited
the cathedral. It does not appear so rich as the smaller church, but
boasts of a little organ, which sent forth singularly inharmonious
cries. We presented the black priest with a few shillings, and the
Spaniard, patting him on the head, said, with much candour, he thought
his colour made no great difference. We then returned, as fast as the
ponies would go, to Porto Praya.
Another day we rode to the village of St. Domingo, situated near the
centre of the island. On a small plain which we crossed, a few stunted
acacias were growing; their tops had been bent by the steady
trade-wind, in a singular manner—some of them even at right angles to
their trunks. The direction
of the branches was exactly north-east by north, and south-west by
south, and these natural vanes must indicate the prevailing direction
of the force of the trade-wind. The travelling had made so little
impression on the barren soil, that we here missed our track, and took
that to Fuentes. This we did not find out till we arrived there; and we
were afterwards glad of our mistake. Fuentes is a pretty village, with
a small stream; and everything appeared to prosper well, excepting,
indeed, that which ought to do so most—its inhabitants. The black
children, completely naked, and looking very wretched, were carrying
bundles of firewood half as big as their own bodies.
Near Fuentes we saw a large flock of guinea-fowl—probably fifty or
sixty in number. They were extremely wary, and could not be approached.
They avoided us, like partridges on a rainy day in September, running
with their heads cocked up; and if pursued, they readily took to the
wing.
The scenery of St. Domingo possesses a beauty totally unexpected, from
the prevalent gloomy character of the rest of the island. The village
is situated at the bottom of a valley, bounded by lofty and jagged
walls of stratified lava. The black rocks afford a most striking
contrast with the bright green vegetation, which follows the banks of a
little stream of clear water. It happened to be a grand feast-day, and
the village was full of people. On our return we overtook a party of
about twenty young black girls, dressed in excellent taste; their black
skins and snow-white linen being set off by coloured turbans and large
shawls. As soon as we approached near, they suddenly all turned round,
and covering the path with their shawls, sung with great energy a wild
song, beating time with their hands upon their legs. We threw them some
vintéms, which were received with screams of laughter, and we left them
redoubling the noise of their song.
One morning the view was singularly clear; the distant mountains being
projected with the sharpest outline, on a heavy bank of dark blue
clouds. Judging from the appearance, and from similar cases in England,
I supposed that the air was saturated with moisture. The fact, however,
turned out quite the contrary. The hygrometer gave a difference of 29.6
degrees, between the temperature of the air, and the point at which dew
was precipitated. This difference was nearly double
that which I had observed on the previous mornings. This unusual degree
of atmospheric dryness was accompanied by continual flashes of
lightning. Is it not an uncommon case, thus to find a remarkable degree
of aerial transparency with such a state of weather?
Generally the atmosphere is hazy; and this is caused by the falling of
impalpably fine dust, which was found to have slightly injured the
astronomical instruments. The morning before we anchored at Porto
Praya, I collected a little packet of this brown-coloured fine dust,
which appeared to have been filtered from the wind by the gauze of the
vane at the masthead. Mr. Lyell has also given me four packets of dust
which fell on a vessel a few hundred miles northward of these islands.
Professor Ehrenberg[3] finds that this dust consists in great part of
infusoria with siliceous shields, and of the siliceous tissue of
plants. In five little packets which I sent him, he has ascertained no
less than sixty-seven different organic forms! The infusoria, with the
exception of two marine species, are all inhabitants of fresh-water. I
have found no less than fifteen different accounts of dust having
fallen on vessels when far out in the Atlantic. From the direction of
the wind whenever it has fallen, and from its having always fallen
during those months when the harmattan is known to raise clouds of dust
high into the atmosphere, we may feel sure that it all comes from
Africa. It is, however, a very singular fact, that, although Professor
Ehrenberg knows many species of infusoria peculiar to Africa, he finds
none of these in the dust which I sent him. On the other hand, he finds
in it two species which hitherto he knows as living only in South
America. The dust falls in such quantities as to dirty everything on
board, and to hurt people’s eyes; vessels even have run on shore owing
to the obscurity of the atmosphere. It has often fallen on ships when
several hundred, and even more than a thousand miles from the coast of
Africa, and at points sixteen hundred miles distant in a north and
south direction. In some dust which was collected on a vessel three
hundred miles from the land, I was much surprised to find particles of
stone above the thousandth of an inch square,
mixed with finer matter. After this fact one need not be surprised at
the diffusion of the far lighter and smaller sporules of cryptogamic
plants.
[3] I must take this opportunity of acknowledging the great kindness
with which this illustrious naturalist has examined many of my
specimens. I have sent (June 1845) a full account of the falling of
this dust to the Geological Society.
The geology of this island is the most interesting part of its natural
history. On entering the harbour, a perfectly horizontal white band in
the face of the sea cliff, may be seen running for some miles along the
coast, and at the height of about forty-five feet above the water. Upon
examination, this white stratum is found to consist of calcareous
matter, with numerous shells embedded, most or all of which now exist
on the neighbouring coast. It rests on ancient volcanic rocks, and has
been covered by a stream of basalt, which must have entered the sea
when the white shelly bed was lying at the bottom. It is interesting to
trace the changes, produced by the heat of the overlying lava, on the
friable mass, which in parts has been converted into a crystalline
limestone, and in other parts into a compact spotted stone. Where the
lime has been caught up by the scoriaceous fragments of the lower
surface of the stream, it is converted into groups of beautifully
radiated fibres resembling arragonite. The beds of lava rise in
successive gently-sloping plains, towards the interior, whence the
deluges of melted stone have originally proceeded. Within historical
times no signs of volcanic activity have, I believe, been manifested in
any part of St. Jago. Even the form of a crater can but rarely be
discovered on the summits of the many red cindery hills; yet the more
recent streams can be distinguished on the coast, forming lines of
cliffs of less height, but stretching out in advance of those belonging
to an older series: the height of the cliffs thus affording a rude
measure of the age of the streams.
During our stay, I observed the habits of some marine animals. A large
Aplysia is very common. This sea-slug is about five inches long; and is
of a dirty yellowish colour, veined with purple. On each side of the
lower surface, or foot, there is a broad membrane, which appears
sometimes to act as a ventilator, in causing a current of water to flow
over the dorsal branchiæ or lungs. It feeds on the delicate seaweeds
which grow among the stones in muddy and shallow water; and I found in
its stomach several small pebbles, as in the gizzard of a bird. This
slug, when disturbed, emits a very fine
purplish-red fluid, which stains the water for the space of a foot
around. Besides this means of defence, an acrid secretion, which is
spread over its body, causes a sharp, stinging sensation, similar to
that produced by the Physalia, or Portuguese man-of-war.
I was much interested, on several occasions, by watching the habits of
an Octopus, or cuttle-fish. Although common in the pools of water left
by the retiring tide, these animals were not easily caught. By means of
their long arms and suckers, they could drag their bodies into very
narrow crevices; and when thus fixed, it required great force to remove
them. At other times they darted tail first, with the rapidity of an
arrow, from one side of the pool to the other, at the same instant
discolouring the water with a dark chestnut-brown ink. These animals
also escape detection by a very extraordinary, chameleon-like power of
changing their colour. They appear to vary their tints according to the
nature of the ground over which they pass: when in deep water, their
general shade was brownish purple, but when placed on the land, or in
shallow water, this dark tint changed into one of a yellowish green.
The colour, examined more carefully, was a French grey, with numerous
minute spots of bright yellow: the former of these varied in intensity;
the latter entirely disappeared and appeared again by turns. These
changes were effected in such a manner that clouds, varying in tint
between a hyacinth red and a chestnut-brown,[4] were continually
passing over the body. Any part, being subjected to a slight shock of
galvanism, became almost black: a similar effect, but in a less degree,
was produced by scratching the skin with a needle. These clouds, or
blushes as they may be called, are said to be produced by the alternate
expansion and contraction of minute vesicles containing variously
coloured fluids.[5]
[4] So named according to Patrick Symes’s nomenclature.
[5] See _Encyclopedia of Anatomy and Physiology_ article
“Cephalopoda.”
This cuttle-fish displayed its chameleon-like power both during the act
of swimming and whilst remaining stationary at the bottom. I was much
amused by the various arts to escape detection used by one individual,
which seemed fully aware that I was watching it. Remaining for a time
motionless, it would then stealthily advance an inch or two, like a cat
after a mouse; sometimes changing its colour: it thus proceeded, till
having
gained a deeper part, it darted away, leaving a dusky train of ink to
hide the hole into which it had crawled.
While looking for marine animals, with my head about two feet above the
rocky shore, I was more than once saluted by a jet of water,
accompanied by a slight grating noise. At first I could not think what
it was, but afterwards I found out that it was this cuttle-fish, which,
though concealed in a hole, thus often led me to its discovery. That it
possesses the power of ejecting water there is no doubt, and it
appeared to me that it could certainly take good aim by directing the
tube or siphon on the under side of its body. From the difficulty which
these animals have in carrying their heads, they cannot crawl with ease
when placed on the ground. I observed that one which I kept in the
cabin was slightly phosphorescent in the dark.
ST. PAUL’S ROCKS.—In crossing the Atlantic we hove-to, during the
morning of February 16th, 1832, close to the island of St. Paul’s. This
cluster of rocks is situated in 0° 58′ north latitude, and 29° 15′ west
longitude. It is 540 miles distant from the coast of America, and 350
from the island of Fernando Noronha. The highest point is only fifty
feet above the level of the sea, and the entire circumference is under
three-quarters of a mile. This small point rises abruptly out of the
depths of the ocean. Its mineralogical constitution is not simple; in
some parts the rock is of a cherty, in others of a feldspathic nature,
including thin veins of serpentine. It is a remarkable fact that all
the many small islands, lying far from any continent, in the Pacific,
Indian, and Atlantic Oceans, with the exception of the Seychelles and
this little point of rock, are, I believe, composed either of coral or
of erupted matter. The volcanic nature of these oceanic islands is
evidently an extension of that law, and the effect of those same
causes, whether chemical or mechanical, from which it results that a
vast majority of the volcanoes now in action stand either near
sea-coasts or as islands in the midst of the sea.
[Illustration]
The rocks of St. Paul appear from a distance of a brilliantly white
colour. This is partly owing to the dung of a vast multitude of
seafowl, and partly to a coating of a hard glossy substance with a
pearly lustre, which is intimately united to the surface of the rocks.
This, when examined with a lens, is
found to consist of numerous exceedingly thin layers, its total
thickness being about the tenth of an inch. It contains much animal
matter, and its origin, no doubt, is due to the action of the rain or
spray on the birds’ dung. Below some small masses of guano at
Ascension, and on the Abrolhos Islets, I found certain stalactitic
branching bodies, formed apparently in the same manner as the thin
white coating on these rocks. The branching bodies so closely resembled
in general appearance certain nulliporæ (a family of hard calcareous
sea-plants), that in lately looking hastily over my collection I did
not perceive the difference. The globular extremities of the branches
are of a pearly texture, like the enamel of teeth, but so hard as just
to scratch plate-glass. I may here mention, that on a part of the coast
of Ascension, where there is a vast accumulation of shelly sand, an
incrustation is deposited on the tidal rocks, by the water of the sea,
resembling, as represented in the picture above, certain cryptogamic
plants (Marchantiæ) often seen on damp walls. The surface of the fronds
is beautifully glossy; and those parts formed where fully exposed to
the light, are of a jet black colour, but those shaded under ledges are
only grey. I have shown specimens of this incrustation to several
geologists, and they all thought that they were of volcanic or igneous
origin! In its hardness and translucency—in its polish, equal to that
of the finest oliva-shell—in the bad smell given out, and loss of
colour under the blowpipe—it shows a close similarity with living
sea-shells. Moreover in sea-shells, it is known that the parts
habitually covered and shaded by the mantle of the animal, are of a
paler colour than those fully exposed to the light, just as is the case
with this incrustation. When we remember that lime, either as a
phosphate or carbonate, enters into the composition of the hard parts,
such as bones and shells, of all living animals, it is an interesting
physiological
fact[6] to find substances harder than the enamel of teeth, and
coloured surfaces as well polished as those of a fresh shell, re-formed
through inorganic means from dead organic matter—mocking, also, in
shape, some of the lower vegetable productions.
[6] Mr. Horner and Sir David Brewster have described (_Philosophical
Transactions_, 1836, p. 65) a singular “artificial substance
resembling shell.” It is deposited in fine, transparent, highly
polished, brown-coloured laminæ, possessing peculiar optical
properties, on the inside of a vessel, in which cloth, first prepared
with glue and then with lime, is made to revolve rapidly in water. It
is much softer, more transparent, and contains more animal matter,
than the natural incrustation at Ascension; but we here again see the
strong tendency which carbonate of lime and animal matter evince to
form a solid substance allied to shell.
We found on St. Paul’s only two kinds of birds—the booby and the noddy.
The former is a species of gannet, and the latter a tern. Both are of a
tame and stupid disposition, and are so unaccustomed to visitors, that
I could have killed any number of them with my geological hammer. The
booby lays her eggs on the bare rock; but the tern makes a very simple
nest with seaweed. By the side of many of these nests a small
flying-fish was placed; which I suppose, had been brought by the male
bird for its partner. It was amusing to watch how quickly a large and
active crab (Graspus), which inhabits the crevices of the rock, stole
the fish from the side of the nest, as soon as we had disturbed the
parent birds. Sir W. Symonds, one of the few persons who have landed
here, informs me that he saw the crabs dragging even the young birds
out of their nests, and devouring them. Not a single plant, not even a
lichen, grows on this islet; yet it is inhabited by several insects and
spiders. The following list completes, I believe, the terrestrial
fauna: a fly (Olfersia) living on the booby, and a tick which must have
come here as a parasite on the birds; a small brown moth, belonging to
a genus that feeds on feathers; a beetle (Quedius) and a woodlouse from
beneath the dung; and lastly, numerous spiders, which I suppose prey on
these small attendants and scavengers of the waterfowl. The
often-repeated description of the stately palm and other noble tropical
plants, then birds, and lastly man, taking possession of the coral
islets as soon as formed, in the Pacific, is probably not quite
correct; I fear it destroys the poetry of this story, that feather and
dirt-feeding and parasitic insects and spiders should be the first
inhabitants of newly formed oceanic land.
The smallest rock in the tropical seas, by giving a foundation
for the growth of innumerable kinds of seaweed and compound animals,
supports likewise a large number of fish. The sharks and the seamen in
the boats maintained a constant struggle which should secure the
greater share of the prey caught by the fishing-lines. I have heard
that a rock near the Bermudas, lying many miles out at sea, and at a
considerable depth, was first discovered by the circumstance of fish
having been observed in the neighbourhood.
FERNANDO NORONHA, _Feb_. 20_th._—As far as I was enabled to observe,
during the few hours we stayed at this place, the constitution of the
island is volcanic, but probably not of a recent date. The most
remarkable feature is a conical hill, about one thousand feet high, the
upper part of which is exceedingly steep, and on one side overhangs its
base. The rock is phonolite, and is divided into irregular columns. On
viewing one of these isolated masses, at first one is inclined to
believe that it has been suddenly pushed up in a semi-fluid state. At
St. Helena, however, I ascertained that some pinnacles, of a nearly
similar figure and constitution, had been formed by the injection of
melted rock into yielding strata, which thus had formed the moulds for
these gigantic obelisks. The whole island is covered with wood; but
from the dryness of the climate there is no appearance of luxuriance.
Half-way up the mountain some great masses of the columnar rock, shaded
by laurel-like trees, and ornamented by others covered with fine pink
flowers but without a single leaf, gave a pleasing effect to the nearer
parts of the scenery.
BAHIA, OR SAN SALVADOR. BRAZIL, _Feb_. 29_th._—The day has past
delightfully. Delight itself, however, is a weak term to express the
feelings of a naturalist who, for the first time, has wandered by
himself in a Brazilian forest. The elegance of the grasses, the novelty
of the parasitical plants, the beauty of the flowers, the glossy green
of the foliage, but above all the general luxuriance of the vegetation,
filled me with admiration. A most paradoxical mixture of sound and
silence pervades the shady parts of the wood. The noise from the
insects is so loud, that it may be heard even in a vessel anchored
several hundred yards from the shore; yet within the recesses of the
forest a universal silence appears to reign. To a person fond of
natural
history, such a day as this brings with it a deeper pleasure than he
can ever hope to experience again. After wandering about for some
hours, I returned to the landing-place; but, before reaching it, I was
overtaken by a tropical storm. I tried to find shelter under a tree,
which was so thick that it would never have been penetrated by common
English rain; but here, in a couple of minutes, a little torrent flowed
down the trunk. It is to this violence of the rain that we must
attribute the verdure at the bottom of the thickest woods: if the
showers were like those of a colder clime, the greater part would be
absorbed or evaporated before it reached the ground. I will not at
present attempt to describe the gaudy scenery of this noble bay,
because, in our homeward voyage, we called here a second time, and I
shall then have occasion to remark on it.
Along the whole coast of Brazil, for a length of at least 2000 miles,
and certainly for a considerable space inland, wherever solid rock
occurs, it belongs to a granitic formation. The circumstance of this
enormous area being constituted of materials which most geologists
believe to have been crystallised when heated under pressure, gives
rise to many curious reflections. Was this effect produced beneath the
depths of a profound ocean? or did a covering of strata formerly extend
over it, which has since been removed? Can we believe that any power,
acting for a time short of infinity, could have denuded the granite
over so many thousand square leagues?
On a point not far from the city, where a rivulet entered the sea, I
observed a fact connected with a subject discussed by Humboldt.[7] At
the cataracts of the great rivers Orinoco, Nile, and Congo, the
syenitic rocks are coated by a black substance, appearing as if they
had been polished with plumbago. The layer is of extreme thinness; and
on analysis by Berzelius it was found to consist of the oxides of
manganese and iron. In the Orinoco it occurs on the rocks periodically
washed by the floods, and in those parts alone where the stream is
rapid; or, as the Indians say, “the rocks are black where the waters
are white.” Here the coating is of a rich brown instead of a black
colour, and seems to be composed of ferruginous matter alone. Hand
specimens fail to give a just idea of these brown burnished stones
which glitter in the sun’s rays. They occur only within
the limits of the tidal waves; and as the rivulet slowly trickles down,
the surf must supply the polishing power of the cataracts in the great
rivers. In like manner, the rise and fall of the tide probably answer
to the periodical inundations; and thus the same effects are produced
under apparently different but really similar circumstances. The
origin, however, of these coatings of metallic oxides, which seem as if
cemented to the rocks, is not understood; and no reason, I believe, can
be assigned for their thickness remaining the same.
[7] _Personal Narrative,_ vol. v, pt. i, p. 18.
[Illustration]
One day I was amused by watching the habits of the Diodon antennatus,
which was caught swimming near the shore. This fish, with its flabby
skin, is well known to possess the singular power of distending itself
into a nearly spherical form. After having been taken out of water for
a short time, and then again immersed in it, a considerable quantity
both of water and air is absorbed by the mouth, and perhaps likewise by
the branchial orifices. This process is effected by two methods: the
air is swallowed, and is then forced into the cavity of the body, its
return being prevented by a muscular contraction which is externally
visible: but the water enters in a gentle stream through the mouth,
which is kept wide open and motionless; this latter action must,
therefore, depend on suction. The skin about the abdomen is much looser
than that on the back; hence, during the inflation, the lower surface
becomes far more distended than the upper; and the fish, in
consequence, floats with its back downwards. Cuvier doubts whether the
Diodon in this position is able to swim; but not only can it thus move
forward in a straight line, but it can turn round to either side. This
latter movement is effected solely by the aid of the pectoral fins; the
tail being collapsed and not used. From the body being buoyed up with
so much air, the branchial openings are out of water, but a stream
drawn in by the mouth constantly flows through them.
The fish, having remained in this distended state for a short time,
generally expelled the air and water with considerable force from the
branchial apertures and mouth. It could emit, at will, a certain
portion of the water, and it appears, therefore probable that this
fluid is taken in partly for the sake of regulating its specific
gravity. This Diodon possessed several means of defence. It could give
a severe bite, and could eject water from its mouth to some distance,
at the same time making a curious noise by the movement of its jaws. By
the inflation of its body, the papillæ, with which the skin is
covered, become erect and pointed. But the most curious circumstance
is, that it secretes from the skin of its belly, when handled, a most
beautiful carmine-red fibrous matter, which stains ivory and paper in
so permanent a manner, that the tint is retained with all its
brightness to the present day: I am quite ignorant of the nature and
use of this secretion. I have heard from Dr. Allan of Forres, that he
has frequently found a Diodon, floating alive and distended, in the
stomach of the shark; and that on several occasions he has known it eat
its way, not only through the coats of the stomach, but through the
sides of the monster, which has thus been killed. Who would ever have
imagined that a little soft fish could have destroyed the great and
savage shark?
_March_ 18_th._—We sailed from Bahia. A few days afterwards, when not
far distant from the Abrolhos Islets, my attention
was called to a reddish-brown appearance in the sea. The whole surface
of the water, as it appeared under a weak lens, seemed as if covered by
chopped bits of hay, with their ends jagged. These are minute
cylindrical confervæ, in bundles or rafts of from twenty to sixty in
each. Mr. Berkeley informs me that they are the same species
(Trichodesmium erythræum) with that found over large spaces in the Red
Sea, and whence its name of Red Sea is derived.[8] Their numbers must
be infinite: the ship passed through several bands of them, one of
which was about ten yards wide, and, judging from the mud-like colour
of the water, at least two and a half miles long. In almost every long
voyage some account is given of these confervæ. They appear especially
common in the sea near Australia; and off Cape Leeuwin I found an
allied, but smaller and apparently different species. Captain Cook, in
his third voyage, remarks that the sailors gave to this appearance the
name of sea-sawdust.
[8] M. Montagne in _Comptes Rendus_, etc. Juillet 1844; and _Annales
des Sciences Naturelles_, December 1844.
[Illustration]
Near Keeling Atoll, in the Indian Ocean, I observed many little masses
of confervæ a few inches square, consisting of long cylindrical threads
of excessive thinness, so as to be barely visible to the naked eye,
mingled with other rather larger bodies, finely conical at both ends.
Two of these are shown above united together. They vary in length from
.04 to .06, and even to .08 of an inch in length; and in diameter from
.006 to .008 of an inch. Near one extremity of the cylindrical part, a
green septum, formed of granular matter, and thickest in the middle,
may generally be seen. This, I believe, is the bottom of a most
delicate, colourless sac, composed of a pulpy substance, which lines
the exterior case, but does not extend within the extreme conical
points. In some specimens, small but perfect spheres of brownish
granular matter supplied the places of the septa; and I observed the
curious process by which they were produced. The pulpy matter of the
internal coating suddenly grouped itself into lines, some of which
assumed a form radiating from a common centre; it then continued, with
an irregular and rapid movement, to contract itself, so that in the
course of a second
the whole was united into a perfect little sphere, which occupied the
position of the septum at one end of the now quite hollow case. The
formation of the granular sphere was hastened by any accidental injury.
I may add, that frequently a pair of these bodies were attached to each
other, as represented above, cone beside cone, at that end where the
septum occurs.
I will here add a few other observations connected with the
discoloration of the sea from organic causes. On the coast of Chile, a
few leagues north of Concepcion, the _Beagle_ one day passed through
great bands of muddy water, exactly like that of a swollen river; and
again, a degree south of Valparaiso, when fifty miles from the land,
the same appearance was still more extensive. Some of the water placed
in a glass was of a pale reddish tint; and, examined under a
microscope, was seen to swarm with minute animalcula darting about, and
often exploding. Their shape is oval, and contracted in the middle by a
ring of vibrating curved ciliæ. It was, however, very difficult to
examine them with care, for almost the instant motion ceased, even
while crossing the field of vision, their bodies burst. Sometimes both
ends burst at once, sometimes only one, and a quantity of coarse,
brownish, granular matter was ejected. The animal an instant before
bursting expanded to half again its natural size; and the explosion
took place about fifteen seconds after the rapid progressive motion had
ceased: in a few cases it was preceded for a short interval by a
rotatory movement on the longer axis. About two minutes after any
number were isolated in a drop of water, they thus perished. The
animals move with the narrow apex forwards, by the aid of their
vibratory ciliæ, and generally by rapid starts. They are exceedingly
minute, and quite invisible to the naked eye, only covering a space
equal to the square of the thousandth of an inch. Their numbers were
infinite; for the smallest drop of water which I could remove contained
very many. In one day we passed through two spaces of water thus
stained, one of which alone must have extended over several square
miles. What incalculable numbers of these microscopical animals! The
colour of the water, as seen at some distance, was like that of a river
which has flowed through a red clay district; but under the shade of
the vessel’s side it was quite as dark as chocolate. The line where the
red and blue water joined was distinctly
defined. The weather for some days previously had been calm, and the
ocean abounded, to an unusual degree, with living creatures.[9]
[9] M. Lesson (_Voyage de la Coquille_, tome i, p. 255) mentions red
water off Lima, apparently produced by the same cause. Peron, the
distinguished naturalist, in the _Voyage aux Terres Australes_, gives
no less than twelve references to voyagers who have alluded to the
discoloured waters of the sea (vol. ii, p. 239). To the references
given by Peron may be added, Humboldt’s _Personal Narrative_, vol. vi,
p. 804; Flinder’s _Voyage_, vol. i, p. 92; Labillardière, vol. i, p.
287; Ulloa’s _Voyage_; _Voyage of the Astrolabe and of the Coquille_;
Captain King’s _Survey of Australia_, etc.
In the sea around Tierra del Fuego, and at no great distance from the
land, I have seen narrow lines of water of a bright red colour, from
the number of crustacea, which somewhat resemble in form large prawns.
The sealers call them whale-food. Whether whales feed on them I do not
know; but terns, cormorants, and immense herds of great unwieldy seals
derive, on some parts of the coast, their chief sustenance from these
swimming crabs. Seamen invariably attribute the discoloration of the
water to spawn; but I found this to be the case only on one occasion.
At the distance of several leagues from the Archipelago of the
Galapagos, the ship sailed through three strips of a dark yellowish, or
mud-like water; these strips were some miles long, but only a few yards
wide, and they were separated from the surrounding water by a sinuous
yet distinct margin. The colour was caused by little gelatinous balls,
about the fifth of an inch in diameter, in which numerous minute
spherical ovules were embedded: they were of two distinct kinds, one
being of a reddish colour and of a different shape from the other. I
cannot form a conjecture as to what two kinds of animals these
belonged. Captain Colnett remarks that this appearance is very common
among the Galapagos Islands, and that the direction of the bands
indicates that of the currents; in the described case, however, the
line was caused by the wind. The only other appearance which I have to
notice, is a thin oily coat on the water which displays iridescent
colours. I saw a considerable tract of the ocean thus covered on the
coast of Brazil; the seamen attributed it to the putrefying carcass of
some whale, which probably was floating at no great distance. I do not
here mention the minute gelatinous particles, hereafter to be referred
to, which are frequently dispersed throughout the water, for they are
not sufficiently abundant to create any change of colour.
There are two circumstances in the above accounts which appear
remarkable: first, how do the various bodies which form the bands with
defined edges keep together? In the case of the prawn-like crabs, their
movements were as coinstantaneous as in a regiment of soldiers; but
this cannot happen from anything like voluntary action with the ovules,
or the confervæ, nor is it probable among the infusoria. Secondly,
what causes the length and narrowness of the bands? The appearance so
much resembles that which may be seen in every torrent, where the
stream uncoils into long streaks the froth collected in the eddies,
that I must attribute the effect to a similar action either of the
currents of the air or sea. Under this supposition we must believe that
the various organised bodies are produced in certain favourable places,
and are thence removed by the set of either wind or water. I confess,
however, there is a very great difficulty in imagining any one spot to
be the birthplace of the millions of millions of animalcula and
confervæ: for whence come the germs at such points?—the parent bodies
having been distributed by the winds and waves over the immense ocean.
But on no other hypothesis can I understand their linear grouping. I
may add that Scoresby remarks that green water abounding with pelagic
animals is invariably found in a certain part of the Arctic Sea.
[Illustration]