TRANSCRIBER’S NOTE
Italic text is denoted by _underscores_.
Footnote anchors are denoted by [number], and the footnotes have
been placed at the end of each chapter. Numbering is unique only
within each chapter.
The tables in this book are best viewed using a monospace font.
Basic fractions are displayed as ½ ⅓ ¼ etc; other fractions are
shown in the form a/b, for example 2/3000.
In the original book the Index page numbering was 609-615, but did
not allow for the insertion of the Addenda pages numbered 609-629.
The Index has been renumbered to 630-636 in this ebook.
Some minor changes to the text are noted at the end of the book.
[Illustration: _SOUTHERN PORTION_
_OF_
SOUTH AMERICA]
[Illustration: KEELING ISLANDS
H.M.S. Beagle
1836.]
VOYAGES
OF THE
ADVENTURE AND BEAGLE.
VOLUME III.
NARRATIVE
OF THE
SURVEYING VOYAGES
OF HIS MAJESTY’S SHIPS
ADVENTURE AND BEAGLE,
BETWEEN
THE YEARS 1826 AND 1836,
DESCRIBING THEIR
EXAMINATION OF THE SOUTHERN SHORES
OF
SOUTH AMERICA,
AND
THE BEAGLE’S CIRCUMNAVIGATION OF THE GLOBE.
IN THREE VOLUMES.
VOL. III.
LONDON:
HENRY COLBURN, GREAT MARLBOROUGH STREET.
1839.
WHITING, BEAUFORT HOUSE, LONDON.
VOLUME III.
JOURNAL AND REMARKS,
1832-1836.
BY
CHARLES DARWIN, ESQ., M.A.
SEC. GEOL. SOC.
PREFACE.
I have stated in the preface to the Zoology of the Voyage of the
Beagle, that it was in consequence of a wish expressed by Captain
FitzRoy, 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 FitzRoy, I hope I may here be
permitted to express my 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 FitzRoy 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.
The present volume contains in the form of a journal, a sketch of
those observations in Geology and Natural History, which I thought
would possess some general interest. As it was originally intended to
have preceded any more detailed account, and as its publication has
been unavoidably delayed, the briefness and imperfection of several
parts, I hope, will be excused. I have given a list of those errata
(partly caused by my absence from town when some of the sheets were
in the press) which affect the sense; and have added an Appendix,
containing some additional facts (especially on the theory of the
transportation of erratic blocks) which I have accidentally met
with during the past year. I hope shortly to publish my geological
observations; the first Part of which will be on the Volcanic Islands
of the Atlantic and Pacific Oceans, and on Coral Formations; and
the second Part will treat of South America. Several numbers of
the Zoology of the Voyage of the Beagle, due to the disinterested
zeal of several of our first naturalists, have already appeared.
These works 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
repeated in this volume my account of the habits of some of the birds
and quadrupeds of South America, as I thought such observations
might interest those readers who would not, probably, consult the
larger work. But I trust that naturalists will remember, that mere
sketches are here given on several subjects, which will hereafter be
more fully entered on, or have already been so:--for instance, the
notices of the strange fossil quadrupeds of the eastern plains of
South America are exceedingly imperfect, whilst an admirable account
of them by Mr. Owen now forms the first part of the Zoology of the
Voyage of the Beagle.
I shall have the pleasure of acknowledging the great assistance I
have received from several naturalists, in the course of this and
the succeeding works; but I must be here allowed to return my most
sincere thanks to the Reverend Professor Henslow, who, when I was
an under-graduate 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.
C. D.
FOOTNOTES:
[1] I must likewise 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.
CONTENTS.
CHAPTER I.
Porto Praya--Ribeira Grande--Dry and clear atmosphere--Effect
of lava on a calcareous beach--Habits of Aplysia and Octopus--St.
Paul’s rocks non-volcanic--Incrustations and stalactites
of phosphate of lime--Insects first colonists--Fernando
Noronha--Bahia--Extent of granite--Burnished rocks--Habits of
Diodon--Pelagic confervæ, infusoria--Causes of discoloured sea 1
CHAPTER II.
Rio de Janeiro--Excursion north of Cape Frio--Great evaporation
--Slavery--Botofogo Bay--Terrestrial Planariæ--Clouds on
Corcovado--Heavy rain--Musical Hyla--Lampyris and its larvæ--Elater,
springing powers of--Blue haze--Noise of butterfly--Entomology--Ants
--Wasp-killing spider--Parasitical spider--Artifices of Epeira
--Gregarious spider--Spider with imperfect web 21
CHAPTER III.
Monte Video--Maldonado--Excursion to R. Polanco--Lazo and Bolas
--Partridges--Geology--Absence of trees--Cervus campestris--River
hog--Tucutuco--Molothrus, cuckoo-like habits of--Tyrant-flycatcher
--Mocking-bird--Carrion hawks--Tubes formed by lightning--House
struck 44
CHAPTER IV.
Rio Negro--Estancias attacked by Indians--Salt lakes, geological
position of--Flamingoes--R. Negro to Colorado--Sacred tree--Patagonian
hare--Indian families--General Rosas--Proceed to Bahia Blanca--Sand
dunes--Negro lieutenant--Bahia Blanca--Ground incrusted with Glauber
salt--Punta Alta--Zorillo 74
CHAPTER V.
Bahia Blanca--Geology--Extinct quadrupeds, four Edentata, horse,
Ctenomys--Recent extinction of--Longevity of species--Large animals
do not require luxuriant vegetation--Southern Africa--Siberian
fossils--Catalogue of extinct quadrupeds of South America--Two
species of Ostrich, habits of--Tinochorus--Oven-bird--Armadilloes
--Venomous snake, toad, lizard--Hybernation of animals--Habits of
sea-pen--Indian wars and massacres--Arrow-head, antiquarian relic 95
CHAPTER VI.
Set out for Buenos Ayres--Rio Sauce--Sierra Ventana--Transportal of
pebbles--Third posta--Driving horses--Bolas--Partridges and
foxes--Features of country--Long-legged plover--Teru-tero--Hailstorm
--Natural enclosures in Sierra Tapalguen--Flesh of puma--Meat diet
--Guardia del Monte--Effects of cattle on the vegetation--Cardoon
--Buenos Ayres--Corral where animals are slaughtered 124
CHAPTER VII.
Excursion to St. Fe--Thistle beds--Habits and range of Bizcacha
--Little owl--Saline streams--Level plains--Mastodon--St. Fe
--Change in landscape--Geology--Tooth of extinct horse--Range of
fossil quadrupeds--Pampas full of remains--Effects of great
droughts--Droughts periodical--Parana--Habits of Jaguar
--Scissor-beak--Kingfisher, parrot, and scissor-tail--Revolution
--Buenos Ayres--State of government 142
CHAPTER VIII.
Monte Video--Excursion to Colonia del Sacramiento--Horses, swimming
--Value of an Estancia--Cattle, how counted--Geology--Great
thistle-beds--Rio Negro--Perforated pebbles--Shepherd dogs--Horses
broken in, Gauchos riding, feats with lazo--Toxodon--Armadillo-like
gigantic covering--Great tail--Return to Monte Video--Character
of inhabitants 167
CHAPTER IX.
Rio Plata--Flocks of butterflies--Beetles alive in the sea--Aeronaut
spiders--Pelagic animals--Phosphorescence of sea--Port Desire--Spanish
settlements--Zoology--Guanaco--Excursion to head of harbour--Indian
grave--Port St. Julian--Geology of Patagonia, successive terraces,
transport of pebbles--Fossil gigantic llama--Types of organization
constant--Change in zoology of America--Causes of extinction 185
CHAPTER X.
Santa Cruz--Expedition up river--Indians--Character of Patagonia
--Basaltic platform--Immense streams of lava--Non-transport of blocks
by river--Excavation of valley--Condor, range and habits--Cordillera
--Erratic boulders of great size--Indian relics--Return to the ship 213
CHAPTER XI.
Tierra del Fuego, first arrival--Good Success Bay--Interview
with savages--Scenery of the forests--Sir J. Banks’s hill--Cape
Horn--Wigwam Cove--Miserable condition of savages--Beagle
channel--Fuegians--Ponsonby Sound--Equality of condition among
the natives--Bifurcation of the Beagle channel--Glaciers--Return
to ship 227
CHAPTER XII.
Falkland Islands--Excursion round island--Aspect--Cattle, horses,
rabbit, wolf-like fox--Fire made of bones--Art in making fire
--Manner of hunting wild cattle--Geology, fossil shells--Valleys
filled with great fragments, scenes of violence--Penguin--Geese
--Eggs of doris--Zoophytes, coralline phosphorescent--Compound
animals 245
CHAPTER XIII.
Strait of Magellan--Port Famine--Geology--Deep water
in channels--Erratic boulders--Climate--Limit of fruit
trees--Mean temperature--Luxuriant forests--Rigour of antarctic
islands--Contrast with the north--Snow-line, great flexure
of--Glaciers--Icebergs transport fragments of rock--Glaciers
in low latitude--Absence of erratic blocks in intertropical
regions--Glaciers and tropical vegetation--Comparison with
northern hemisphere--Siberian animals in ice--Embedded in cold
mud--Edible fungus--Zoology--Fucus giganteus--Leave Tierra del
Fuego 263
CHAPTER XIV.
Valparaiso--Excursion to base of Andes--Structure of land--Ascend
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 puma--El turco
and tapacolo--Humming-birds 308
CHAPTER XV.
Chiloe--General aspect--Boat excursion--Native Indians--Castro
--Large leaves of Gunnera scabra--Tame fox--Ascend San Pedro--Chonos
Archipelago--Peninsula of Tres Montes--Granitic range--Lowe’s
Harbour--Wild potato--Forest--Formation of peat--Myopotamus,
otter and mice--Cheucau and barking-bird--Furnarius--Singular
character of ornithology--Petrels 333
CHAPTER XVI.
San Carlos, Chiloe--Osorno in eruption--Ride to Castro and Cucao
--Impenetrable forests--Valdivia--Apple-trees--Ride to Llanos
--Indians--Earthquake--Concepcion--Great earthquake--Effects of
wave--Rocks fissured--Appearance of the former towns--Water in the
bay black and boiling--Direction of vibration--Stones displaced
--Cause of great waves--Permanent elevation of land--Great lake
of fluid rock beneath crust of the globe--Connexion of volcanic
phenomena--Slow elevation of mountain chains, cause of earthquakes 356
CHAPTER XVII.
Valparaiso--Passage of Andes by Portillo pass--Sagacity of
mules--Mountain torrents--Mines, how discovered--Marine alluvium
in valleys--Effect of snow on surface--Geology, fossil shells,
double range, two periods of elevation--Red snow--Winds on the
crest--Snow thawing in pinnacles--Dry and clear atmosphere
--Electricity--Pampas--Zoology of opposite sides of Andes--Uniformity
of Patagonia--Locusts--Great bugs--Mendoza--Uspallata--Silicified
trees in vertical position--Indian ruins--Change of climate
--Earthquake arching bed of river--Cumbre--Valparaiso 382
CHAPTER XVIII.
Bell mountain--Miners--Great loads carried by the Apires--Coquimbo
--Earthquake--Geology--Terraces--Excursion up valley--Road to
Guasco--Desert country--Valley of Copiapó--Rain and earthquakes,
meteorolites--Hydrophobia--Copiapó--Excursion to Cordillera--Dry
valley--Cold gales of wind--Noises from a hill--Iquique, complete
desert--Salt alluvium--Nitrate of soda--Lima--Unhealthy country
--Ruins of Callao, overthrown by earthquake--Elevated shells on
island of San Lorenzo--Plain with embedded fragments of pottery 416
CHAPTER XIX.
Galapagos Islands volcanic--Number of craters--Leafless bushes
--Colony at Charles Island--James Island--Salt-lake in crater
--Character of vegetation--Ornithology, curious finches--Great
tortoises, habits of, paths to the wells--Marine lizard feeds on
sea-weed--Terrestrial species, burrowing habits, herbivorous
--Importance of reptiles in the Archipelago--Few and minute
insects--American type of organization--Species confined to certain
islands--Tameness of birds--Falkland Islands--Fear of man an
acquired instinct 453
CHAPTER XX.
Tahiti--Aspect of--Vegetation on the slope of the mountains--View
of Eimeo--Excursion in the interior--Profound ravines--Succession
of waterfalls--Number of wild useful plants--Temperance of
inhabitants--Their moral state--Parliament convened--New Zealand
--Bay of islands--Hippahs--Absence of all government--Excursion
to Waimate--Missionary establishment--English weeds now run
wild--Waiomio--Funeral service--Sail from New Zealand 479
CHAPTER XXI.
Sydney--Prosperity of--Excursion to Bathurst--Aspect of woods--Party
of Natives--Gradual extinction of aborigines--Blue Mountains
--Weatherboard--View of a grand gulf-like valley--Sheep farm
--Lion-ant--Bathurst, general civility of lower orders--State of
society--Van Diemen’s Land--Hobart Town--Aborigines all banished
--Mount Wellington--King George’s Sound--Cheerless aspect of
country--Bald Head, calcareous casts like branches of trees--Party
of natives--Leave Australia 515
CHAPTER XXII.
Keeling Island--Singular appearance of--Scanty Flora--Transport of
seeds--Birds and insects--Ebbing and flowing springs--Coral
formations resisting power of ocean--Fields of dead coral--Stones
transported by roots of trees--Great crab--Stinging corals
--Structure of lagoon islands--Encircling and Barrier reefs--General
proofs of subsidence in the Pacific--Theory of lagoon islands caused
by subsidence of the land--Pacific and Indian oceans divided into
alternate areas of elevation and subsidence--Points of eruption
lie within the areas of elevation 539
CHAPTER XXIII.
Mauritius, beautiful appearance of--Hindoos--Cape of Good Hope--St.
Helena--Geology--History of changes in vegetation, probable cause
of extinction of land-shells--Ascension--Green Hill--Curious
incrustations of calcareous matter on tidal rocks--Bahia--Brazil
--Splendour of tropical scenery--Pernambuco--Singular reef--Azores
--Supposed crater--Hints to collectors--Retrospect of the most
impressive parts of the voyage 570
ADDENDA 609
INDEX. 630
JOURNAL
OF
CHARLES DARWIN, M.A.,
NATURALIST TO THE BEAGLE.
CHAPTER I.
Porto Praya--Ribeira Grande--Dry and clear atmosphere--Effect
of lava on calcareous beach--Habits of Aplysia and Octopus--St.
Paul’s rock non-volcanic--Incrustations and stalactites
of phosphate of lime--Insects first colonists--Fernando
Noronha--Bahia--Extent of granite--Burnished rocks--Habits of
Diodon--Pelagic confervæ, infusoria--Causes of discoloured sea.
ST. JAGO--CAPE DE VERD ISLANDS.
JAN. 16TH, 1832.--The neighbourhood of Porto Praya, viewed from the
sea, wears a desolate aspect. The volcanic fire of past ages, and
the scorching heat of a tropical sun, have in most places rendered
the soil sterile and 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 the sea, and who has just walked, for the first
time, in a grove of cocoa-nut trees, can be a judge of any thing
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 prospect 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. At the present time it has not
rained for an entire year. The broad, flat-bottomed, valleys, many of
which serve during a few days only in the season as a watercourse,
are clothed with thickets of leafless bushes. Few living creatures
inhabit these valleys. The commonest bird is a kingfisher (_Dacelo
jagoensis_), which tamely sits on the branches of the castor-oil
plant, and thence darts on the 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 valleys, there is also a wide difference.
One day, two of the officers and myself rode to Ribeira Grande, a
village a few miles to the eastward of Porto Praya. Until we reached
the valley of St. Martin, the country presented its usual dull
brown appearance; but there, 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. The 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.[1] 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.
We returned to the “Vênda” to eat our dinners. A considerable number
of men, women, and children, all as black as jet, were collected to
watch us. Our companions were extremely merry; and every thing 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 most
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, by the action of the steady
trade-wind, were bent in a singular manner--some of them even at a
right angle to the trunk. The direction of the branches was exactly
N.E. by N., and S.W. by S. 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 very glad of our mistake.
Fuentes is a pretty village, with a small stream; and every thing
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 most
excellent taste; their black skins and snow-white linen being set off
by their 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.
It has already been remarked, that the atmosphere is generally very
hazy; this appears chiefly due to an impalpable dust, which is
constantly falling, even on vessels far out at sea. The dust is of
a brown colour, and under the blowpipe easily fuses into a black
enamel. It is produced, as I believe, from the wear and tear of
volcanic rocks, and must come from the coast of Africa. 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?
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, such
as 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. For a thickness of several
inches it is converted, in some parts, into a firm stone, as hard as
the best freestone; and the earthy matter, originally mingled with
the calcareous, has been separated into little spots, thus leaving
the limestone white and pure. In other parts a highly crystalline
marble has been formed, and so perfect are the crystals of carbonate
of lime, that they can easily be measured by the reflecting
goniometer. The change is even more extraordinary, where the lime
has been caught up by the scoriaceous fragments of the lower surface
of the stream; for it is there 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 originally proceeded. Within historical
times, no signs of volcanic activity have, I believe, been manifested
in any part of St. Jago. This state of quiescence is, probably, owing
to the neighbouring island of Fogo being frequently in eruption. Even
the form of a crater can but rarely be discovered on the summits of
any of the red cindery hills; yet the more recent streams can be
distinguished on the coast, forming a line of cliffs of less height,
but stretching out in advance of those belonging to an older series:
the height of the cliff thus affording a rude measure of the age.
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. At
the anterior extremity, it has two pair of feelers; the upper ones
of which resemble in shape the ears of a quadruped. 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. It feeds on delicate sea-weeds,
which grow among the stones in muddy and shallow water; and I found
in its stomach several small pebbles, as in the gizzards of birds.
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
the 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 gray, 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,[2] 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, when examined under a glass, are described as
being produced by the alternate expansions and contractions of minute
vesicles, containing variously-coloured fluids.[3]
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 did not
know what it was, but afterwards I found out that it was the
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 certain that it could,
moreover, 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, close to the island of St. Paul.
This cluster of rocks is situated in O° 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 felspathic nature; and in the latter case it contains
thin veins of serpentine, mingled with calcareous matter.
The circumstance of these rocks not being of volcanic origin is of
interest, because, with very few exceptions, the islands situated in
the midst of the great oceans are thus constituted. As the highest
pinnacles of the great mountain ranges probably once existed as
islands distant from any continent, we are led to expect that they
would frequently consist of volcanic rocks. It becomes, therefore, a
curious point to speculate on the changes which many of the present
islands would undergo, during the lapse of the countless ages, which
would be required to elevate them into snow-clad summits. If we
take the case of Ascension, or St. Helena, both of which have long
existed in an extinct condition, we may feel assured, before so vast
a period could elapse, during the whole of which the surface would
be exposed to constant wear and tear, that the mere nucleus or core
of the island would remain; perhaps, every fragment of cellular rock
having been decomposed, a mass of some compact stone, as phonolite or
greenstone, would crown our new Chimborazo.
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 glossy white substance, 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. The surface
is smooth and glossy, and has a pearly lustre; it is considerably
harder than calcareous spar, although it can be scratched by a knife:
under the blowpipe it decrepitates, slightly blackens, and emits a
fetid odour. It consists of phosphate of lime, mingled with some
impurities; and its origin without doubt is due to the action of the
rain or spray on the bird’s dung. I may here mention, that I found
in some hollows in the lava rocks of Ascension considerable masses
of the substance called _guano_, which on the west coast of the
intertropical parts of South America occurs in great beds, some yards
thick, on the islets frequented by seafowl. According to the analysis
of Fourcroy and Vauquelin, it consists of the urates, phosphates,
and oxalates of lime, ammonia, and potash, together with some other
salts, and some fatty and earthy matter. I believe there is no doubt
of its being the richest manure which has ever been discovered. At
Ascension, close to the _guano_, stalactitic or botryoidal masses
of impure phosphate of lime adhered to the basalt. The basal part
of these had an earthy texture, but the extremities were smooth
and glossy, and sufficiently hard to scratch common glass. These
stalactites appeared to have shrunk, perhaps from the removal of some
soluble matter, in the act of consolidation; and hence they had an
irregular form. Similar stalactitic masses,[4] though I am not aware
that they have ever been noticed, are, I believe, by no means of
uncommon occurrence.
We only observed 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 visiters,
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 sea-weed. 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 birds. Not a single plant, not even a lichen, grows
on this island; yet it is inhabited by several insects and spiders.
The following list completes, I believe, the terrestrial fauna:
a species of Feronia and an acarus, which must have come here as
parasites on the birds; a small brown moth, belonging to a genus that
feeds on feathers; a staphylinus (_Quedius_) and a woodlouse from
beneath the dung; and lastly, numerous spiders, which I suppose prey
on these small attendants on, and scavengers of the waterfowl. The
often-repeated description of the first colonists of the coral islets
in the South Sea, is not, probably, quite correct: I fear it destroys
the poetry of the story to find, that these little vile insects
should thus take possession before the cocoa-nut tree and other noble
plants have appeared.
The smallest rock in the tropical seas, by giving a foundation, for
the growth of innumerable kinds of sea-weed and compound animals,
supports likewise a large number of fish. The sharks and the seamen
in the boats maintained a constant struggle, who should secure the
greater share of the prey caught by the lines. I have heard, that a
rock near the Bermudas, lying many miles out at sea, and covered by a
considerable depth of water, was first discovered by the circumstance
of fish having been observed in the neighbourhood.
FERNANDO NORONHA, FEB. 20TH.--As far as I was enabled to observe,
during the few hours we staid 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. From the first impression, on viewing one of
these isolated masses, one is inclined to believe, that the whole
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 among the yielding strata; which thus formed the model for these
gigantic obelisks. The whole island is covered with wood; but from
the dryness of the climate there is no appearance of luxuriance. At
some elevation great masses of the columnar rock, shaded by laurels,
and ornamented by a tree covered by fine pink flowers like those of
a foxglove, but without a single leaf, gave a pleasing effect to the
nearer parts of the scenery.
BAHIA, OR SAN SALVADOR. BRAZIL, FEB. 29TH.--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 been wandering
by himself in a Brazilian forest. Among the multitude of striking
objects, the general luxuriance of the vegetation bears away the
victory. The elegance of the grasses, the novelty of the parasitical
plants, the beauty of the flowers, the glossy green of the foliage,
all tend to this end. 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 ever can hope again to experience. 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 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.
The geology of the surrounding country possesses little interest.
Throughout the coast of Brazil, and certainly for a considerable
space inland, from the Rio Plata to Cape St. Roque, lat. 5° S., a
distance of more than 2000 geographical miles, wherever solid rock
occurs, it belongs to a granitic formation. The circumstance of this
enormous area being thus constituted of materials, which almost
every geologist believes to have been crystallized by the action of
heat 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.[5]
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.” The coating is here of a rich brown
instead of a black colour, and seems to be composed of ferrugineous
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 tidal action; and as the rivulet slowly trickles
down, the surf must supply the polishing power of the cataracts in
the great rivers. In the same manner, the rise and fall of the tide
probably answers to the periodical inundations; and thus the same
causes are present under apparently very different circumstances. The
real 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 constant.
One day I was amused by watching the habits of a Diodon, which was
caught swimming near the shore. This fish 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 was absorbed by the mouth, and perhaps likewise by the
branchial apertures. 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, I observed, entered in a stream through the
mouth, which was wide open and motionless: this latter action must,
therefore, depend on suction. The skin about the abdomen is much
looser than that of 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 likewise 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 were
out of water; but a stream drawn in by the mouth, constantly flowed
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 it made a curious noise by the movement
of its jaws. By the inflation of its body, the papillæ, with which
the skin is covered, became erect and pointed. But the most curious
circumstance was, that it emitted from the skin of its belly, when
handled, a most beautiful carmine red and fibrous secretion, which
stained 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.
MARCH 18TH.--We sailed from Bahia. A few days afterwards, when not
far distant from the Abrolhos islets, my attention was called to a
discoloured 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. One of the larger particles
measured .03 of an inch in length, and .009 in breadth. Examined
more carefully, each is seen to consist of from twenty to sixty
cylindrical filaments, which have perfectly rounded extremities, and
are divided at regular intervals by transverse septa, containing a
brownish-green flocculent matter. The filaments must be enveloped in
some viscid fluid, for the bundles adhered together without actual
contact. I do not know to what family these bodies properly belong,
but they have a close general resemblance in structure with the
confervæ which grow in every ditch. These simple vegetables, thus
constituted for floating in the open ocean, must in certain places
exist in countless numbers. 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. Off Cape
Leeuwin, I found some very similar to those above described; they
differed chiefly in the bundles being rather smaller, and being
composed of fewer filaments. Captain Cook, in his third voyage,
remarks, that the sailors gave to this appearance the name of
sea-sawdust.
I may here mention that during two days preceding our arrival at the
Keeling Islands in the Indian Ocean, I saw in many parts masses of
flocculent matter, of a brownish-green colour, floating in the sea.
They varied in size, from half to three or four inches square; and
were quite irregular in figure. In an opake vessel they could barely
be distinguished, but in a glass one they were clearly visible.
Under the microscope the flocculent matter was seen to consist of
two kinds of confervæ, between which I am quite ignorant whether
there exists any connexion. Minute cylindrical bodies, conical at
each extremity, are involved in vast numbers, in a mass of fine
threads. These threads have a diameter of about 2/3000 of an inch;
they possess an internal lining, and are divided at irregular and
very wide intervals by transverse septa. Their length is so great,
that I could never with certainty ascertain the form of the uninjured
extremity; they are all curvilinear, and resemble in mass a handful
of hair, coiled up and squeezed together. In the midst of these
threads, and probably connected by some viscid fluid, the other kind,
or the cylindrical transparent bodies, float in great numbers. These
have their two extremities terminated by cones, produced into the
finest points: their diameter is tolerably constant between .006 and
.008 of an inch; but their length varies considerably from .04 to
.06, and even sometimes to .08. 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 sack, composed of a pulpy substance, which
lines the exterior case, but does not extend within the extreme
conical points. In some, small but perfect spheres of brownish
granular matter supplied the place 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 appearance was as if an elastic membrane,
for instance a thin Indian-rubber ball, had been distended with air,
and then burst, in which case the edges would instantly shrink up
and contract towards a point. 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 in
the accompanying rude drawing, cone beside cone, at that end where
the septum occurs. When floating uninjured in the sea, the formation
of the spherical gemmules perhaps only takes place, when two of
the plants (or rather animals, according to Bory St. Vincent) thus
become attached, and married to each other. Nevertheless, I certainly
witnessed this curious process in several individuals, when separate,
and where there was no apparent cause of disturbance. In any case it
does not seem probable, from the fixed structure of the septum, that
the whole of the granular matter is transferred from one to the other
body, as with the true Conjugatæ.
[Illustration: (cross-sectional drawing of paired cones.)]
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; and again, a degree south of
Valparaiso, the same appearance was still more extensive. Although
we were nearly fifty miles from the coast, I at first attributed
this circumstance to real streams of muddy water brought down by the
river Maypo. Mr. Sulivan, however, having drawn up some in a glass,
thought he distinguished, by the aid of a lens, moving points. The
water was slightly stained as if by red dust; and after leaving it
for some time quiet, a cloud collected at the bottom. With a lens,
of one-fourth of an inch focal distance, small hyaline points could
be seen darting about with great rapidity, and frequently exploding.
Examined with a much higher power, their shape was found to be oval,
and contracted by a ring round the middle, from which line curved
little setæ proceeded on all sides; and these were the organs of
motion. One end of the body was narrower and more pointed than the
other. According to the arrangement of Bory St. Vincent, they are
animalcula, belonging to the family of Trichodes: 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, which
cohered very slightly. The ring with the setæ sometimes retained its
irritability for a little while after the contents of the body had
been emptied, and continued a riggling, uneven motion. 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. In Ulloa’s voyage an account is given of crossing, in
nearly the same latitude, some discoloured water, which was mistaken
for a shoal: no soundings were obtained, and I have no doubt, from
the description, that this little animalcule was the cause of the
alarm.[6]
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
unwieldly seals, on some parts of the coast, derive 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 surface 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 surface 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 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 very
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 any thing 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 organized 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.
FOOTNOTES:
[1] The Cape de Verd Islands were discovered in 1449.
[2] So named according to Pat. Symes’s nomenclature.
[3] See Encyclo. of Anat. and Physiol., article _Cephalopoda_.
[4] I may mention that I was shown, at Ascension, some very fine
stalactites, composed of sulphate of lime, which had been taken out
of a cavern. From their external appearance they would generally be
mistaken for the ordinary calcareous kind. It was interesting to
observe, in a fractured specimen, the double cleavage intersecting
with its even planes, the irregular layers of successive deposition.
[5] Pers. Narr., vol. v., pt. i., p. 18.
[6] M. Lesson (Voyage de la Coquille, vol. 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). It was his
intention to have written an essay on the subject. To the references
given by Peron may be added, Humboldt’s Pers. Narr., vol. vi., p.
804; Flinder’s Voyage, vol. i., p. 92; Labillardiere, vol. i., p.
287; Ulloa’s Voyage; Voyage of the Astrolabe and of the Coquille;
Captain King’s Survey of Australia, &c.