Rodolfo Amedeo Lanciani.

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* Journal of the Royal Geographical Society, vol zxxiz.

t Foster m *♦ Mississippi Valley," p. 338, and' A. Gteikie m " Nature," roL i, p. 436.



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Extracts from Mr. Bentham's Address. 826



Art. XXXI. — Extracts from the Address q/" George Bentham,
Esq., President of the Linnean Society, on the 20th of May,
1870.

It had been mv intention on the present occasion to carry on
the sketches of the general progress of biological science which
I had attempted in 1862, 1864, 1866, and 1868; but I have,
from various causes, been unable to devote so much time as
usual to the preparation of my Address, and feel obliged to
confine myself to a few points connected with subjects of spe-
cial interest to myself, which, within the last two or three years,
have made considerable advances.

The most striking are, without doubt, the results obtained
from the recent explorations of the deep-sea faunas, and from
the investigation of the tertiary deposits of the arctic regions,
which, although aflFecting two very different branches of natu-
ral science, I here couple together, as tending, both of them, to
elucidate in a remarkable de^ee one of the most important
among the disputed questions m biological history, the contin-
uity of life through successive geological periods.

An excellent general sketch of the first discovery and pro-
gressive investigation of animal life at the bottom of the sea at
great depths, up to the close of the season of 1868, is given by
Dr. Carpenter m the Proceedings of the Royal Society, vol
xvii. No. 107, for Dea 17, 1868. The results of the still more
important expedition of the past year have as yet been only
generally stated by Mr. Gwyn Jeffreys, in the numbers of * Na-
ture ' for Dec 2 and 9, 1869, and by Dr. Carpenter, in a lecture
to the Royal Institution, published in the numbers of * Scien-
tific Opinion ' for March 23 and 80 and April 6 and 18 of the
present year ; and further details, as to the Madreporaria, are
given by Mr. Duncan in the Proceedings of the Royal Society,
voL xviii, No. 118, for March 24 of the present year ; whilst,
in North America, the chief conclusions to be drawn from these
researches into the deep-sea fauna are clearly and concisely enu-
merated by Prof Verrill, in the American Journal of Science for
January last; and some of the more detailed reports of the
American explorations, by Louis and Alexander Acassiz and
others, have been published in the Bulletin of the Museum of
Comparative Zoology at Harvard College, Nos. 6, 7, and 9 to
13. For the knowledge of the data furnished by the tertiary
deposits of the arctic r^ons we are indebted almost exclusively
to the acute observations and able elucidations of Prof 0.
Heer, in his * Flora Fossilis Arctica,* in his paper on the fossil

!)lants collected by Mr. Whymper in Nortn Greenland, pub-
ished in the last part of the rhilosophical Transactions for



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326 Extracts from Mr. Bentham's Address.

1869, and in the as vet only short general sketch of the results of
the Swedish Spitzoe^en Expeditions, contained in the Gene*
vese * Bibliotheque LJniverselle, Archives Scientifiques,' for
Dec. 1869.

It would be useless for me here to retrace, after Dr. Carpen-
ter and Prof. Verrill, the outlines of the revolution which tnese
marine discoveries have caused in the previoualy conceived the-
ories, both as to the geographical distribution of marine ani-
mals, and the relative influences upon it of temperature and
depth, and as to the actual temperature of the deep seas, or to
enter into any details of the enormous additions thus made to
our knowledge of the diversities of organic life ; and it would
be still ftirther fix>m my province to consider the geological
conclusions to be drawn ttom them. My object is more espe-
cially to point out how these respective dips into the eariv his-
tory of marine animals and of terrestrial forests have a£K>rded
the strongest evidence we have yet obtained, that apparently
unlimited permanency and total change can go on aide by side,
without reauiring for the latter any general catastrophe that
should preclude tne former.

There was a time, as we learn, when our chalk-diflfe, now
high and dry, were being formed at the bottom of the sea bv
the gradual growth and decay of Globigerinse and the animals
that fed on them — amongst others, for instance, Bhizocrintis
and TerebratiUina capvi-servmtis; and when, at a later period,
the upheaval of the ground into an element where these animals
could no longer live arrested their progress in that direction,
they had already spread over an area suflSciently extensive for
some part of their race to maintain itself undisturbed ; and so,
on from that time to the present day, by gradual dispersion or
migration, in one direction or another, the same Khizocrinus
and Terebratulina have always been in possession of some genial
locality, where they have continued from generation to genera-
tion, and still continue, with Globigerinee and other animals,
forming chalk at the bottom of the sea, unchanged in structural
character, and rigidly conservative in habits and mode of life
through the vast geological period they have ¥ritnessed. So
rfso there was a tmie when the hill-sides of Greenland and
Spitzbergen, now enveloped in never-melting ice and snows,
were, under a genial climate, clothed with forests, in which
flourished Taxodium distichum (with SequmXy Magnolios^ and
when at a later period these forests were d!estroyed by the gene-
ral refrigeration, the Taxodium already occupied an area exten-
sive enough to include some districts in which it could stUl live
and propj^te; and whatever vicissitudes it may have met
with in some parts, or even in the whole, of its original area,
it has, by gradual extension and migration, always found some



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Exkvctsfrom Mr. Bentham^s Address. 827

spot where it haa gone on and thriven, and continued its race
from generation to generation down to the present day, un-
changed in character and unmodified in its i^pquirements. In
both cases, the permanent animals of the deep-sea bottom and
the permanent trees of the terrestrial forests have witnessed a
more or less partial or complete change in the races amongst
which they were commingled Some of these primitive associ-
ates, not endowed with tne same means of dispersion, and con-
fined to their original areas, were extinguished by the geological
or climatological changes, and replaced by other races amongst
which the permanent ones had penetrated, or by new immi-
grants fipom other areas ; others, again, had spread like the per-
manent ones, but were less fitted for the new conditions in
which they had been placed, and in the course of successive
generations had been gradually modified by the Darwinian pro-
cess of natural selection, the survival of the fittest only among
their descendants. If, in after times, the upheaved sea-bottom
becomes again submerged, the frozen land becomes again sidted
for v^etation, they are again respectively covered with marine
animak or vegetable life, derived irom more or less adjacent
r^ions, and more or less different fi'om that which they origin-
ally supported, in proportion to the lapse of time and extent
of physical changes which had intervened. Thus it is that we
can perfectly agree with Mr. Duncan, that " this persistence (of
type and species through ages, whilst their surroundings were
changed over and over again) does not indicate that there have
not been suflScient physical and biological changes during its
lasting to alter the face of all things enough to give geologists
the right of asserting the succession of several periods :" but
we can, at the same time, feel that Dr. Carpenter is in one sense
justified in the proposition, that we may be said to be still living
in the Cretaceous period. The chalk formation has been going
on over some part of the North Atlantic sea-bed, firom its first
commencement to the present day, in unbroken continuity and
unchanged in character.

If once we admit as demonstrated the coexistence of indefi-
nite permanency and of gradual or rapid change in difierent
races in the same area, and under the same physical conditions,
according to their constitutional idiosyncracies, and also that
one and the same race may be permanent or more or less <^hang'
ing, according to local, climatological, or other physical condi-
tions in which it may be placed, we have removed one of the
great obstacles to the investigation of the history of races, the
apparent want of uniformity in the laws which r^ulate the
succession of forms. We may not only trace, with more confi-
dence, such modifications of race through successive geological
periods as Pro£ Huxley has recently exhibited to us in respect



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828 Extracts from Mr. BenOiarrCa Address

of the Horse, but we can understand more readily the absolute
identity of certain species of plants inhabiting widely dissev-
ered areas, of which the great majority of species are more or
less different One of the arguments brought forward against
the community of origin of representative species in distant
regions, such as temperate Europe and the Australian Alps,
the Arctic Circle ana Antarctic America, the Eastern United
States and Japan respectively — ^an argument which has long
appeared to me to have considerable weight — ^was this : — ^if dis-
severance and subsequent isolation result necessarily in a grad-
ual modification by natural selection, how is it that when all
are subjected to the same influences, the descendants of some
races have become almost generically distinct in the two r^ons,
whilst others are universally acknowledged as congeners, but
specifically distinct, and others again are only slight varieties
or have remained absolutely identical ? To this we can now
reply, with some confidence, that there is no more absolute uni-
formity in the results of natural selection than in any other of
the phenomena of Ufa External influences act differently
upon different constitutions. Were we to remove the whole
flora and fauna of a country to a distant region, or, what comes
to the same thing, change the external conditions of that flora
and fauna, as to climate, physical influences, natural enemies,
or other causes of destruction, means of protection, &c., we
should now be taught to expect that some of the individual
races would at once perish ; others, more or less affected, might
continue through several generations, but with decreasing vigor,
and, in the course of years or ages, gradually die out, to be re-
placed by more vigorous neighbors or invaders. Others, again,
might see amongst their numerous and ever Varying offspring
some few slightly modified, so as to be better suited for the
new order of things ; and experience has repeatedly shown that
the change once begun may go on increasing through successive
generations and a permanent representative species maj be
formed. And some few races might find themselves quite as
happy and vigorous under their new circumstances as under
the old, and might go on as before, unchanged and unchanging.
Taking into consideration the new lights that have been
thrown upon these subjects by the above investigations and by
the numerous observations called forth hj the aevelopment of
the great Darwinian theories, amongst which I may include a
few points adverted to in a paper on Cassia which I laid before
you last year, but which a press of matter has prevented our
yet sending to press, it appears to me that, in plants at least,
we may almost watch, as it were, the process of specific change
actually going on ; or at least we may observe different races
now living in different stages of progress, fix)m the slight local



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Extracts from Mr. BenihmrCs Address, 829

variation to the distinct species and genus. As the first step
we may take, for instance, those races which are r^arded by
the majority of botanists as variable species, such as Rxjtbusfru-
ticosus,, Rosa canina^ Zomia diphyUa^ Cassia mimosoides^ &c.
"We shall find in each some one form, which we call typical,
generally prevalent over the neater part of the area of the race,
whilst others, more or less aberrant, are more or less restricted
to particular localities, the same varieties not occurring in dis-
connected stations with precisely the same combinations of char-
acter and in the same proportions; local and representative
varieties and subspecies are being formed, but have not yet
obtained suflScient advantages to prevent their being kept in
check by their intercommunication (and, wobably, cross-breed-
ing) with their more robust type. The British Batologist or
Ehodologist transported to the south of France or to Hungary
will still find one, or perhaps two or three forms of Bramble
and I)og-rose with which he is familiar ; but if he wishes to
discriminate the thirty or forty varieties or subspecies upon
which he had spent so much labor and acuteness at home, he
must recommence with a series of forms and combinations of
characters quite new to him. The species is still the same ; the
varieties are changed. As examples of what we may call a sec-
ond stage in the formation of species, we may adduce such
plants as Pelargonium australe or grossvlarioides and Nicotiana
suaveolens or angusiifolia^ to which I alluded in the above-men-
tioned paper on Cassia. Here we have one race, of no higher
than specific grade in the ordinary acceptance of the term, in-
habiting two countries which have long been widely dissevered
(in the one case South Africa and Australia, in the other Chili
and Australia), which, if originally introduced by accident from
one country to the other, have been so at a time so remote as
thoroughly to have acquired an indigenous character in both ; in
both they are widely spread and hignly diversified : but among
all their varieties one form only is identical in the two countries
{Pelargonium australe^ var. erodioides^ and P. grossularioides^ var.
anceps; Nicotiana suaveolens^ var. angustifolia^ and N. angvstifo-
lia^ var. acumtnata\ and that so comparatively a rare one that
it may be regarded as being in the course of extinction ; whilst
all other varieties, some of them very numerous in individuals
over extended areas, and all connected by nice gradations, di-
verge nevertheless in the two countries in diflFerent directions
and with different combinations of characters, no two of them
growing in the two countries being at all connected but through
the medium of that one which is still common to both. When
that shall have expired, the distinct species may be considered
established. A still further advance in specific change is exem-
Ajf. JomL Sol— SxooND Sbbibs, Vol. L, No. ISO.—Nov., 1870.
21



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880 ExtrojctB from Mr. Bentham^s Address.

plified in Cdssia itself, in which I have shown that no leas than
eight or nine different modifications of type, sectional and sub-
sectional, are common to South America, tropical Africa, and
Australia, but without anv specific or, at least, subspecific iden-
tity, except perhaps in a few cases where a more modem inter-
change may be presumed. The original common specific types
are extinct, the species have risen into sections. Common
tvpes of a still higher order have disappeared in the case of
f roteaceae, an order so perfectly natural and so clearly defined
that we cannot refrain from speculatmg on the community of
origin of the Afiican and of the Australian races, both exceed-
ingly numerous and reducible to definite groups — ^laige and
small well-marked genera in both countries, and yet not a sin-
gle genus common to the two; not only the species, but the
genera themselves have become geographical As in the case
of the varieties of Pelargonium and Nicotianaj so in that of the
species of Oassia and of the genera of Proteaceae, it is not to be
dienied that precisely similar modifications of character are ol>
served in the two countries ; but these modifications are differ-
entiy combined, the changes in the organs are differently corre-
lated. In Asiatico- African Chamcecristxje a tendency to a par-
ticular change in the venation of the leaflet is accompanied by
a certain change in the petiolar gland ; in America the same
change in the gland is correlated with a different alteration in
the venation. In Australian Proteaceae the glands of the torus
are constantiy deficient with a certain inflorescence (cones with
imbricate scales) which is always accompanied by them in Africa.

In selecting the above instance for illustration of what we
may, without much strain upon the imagination, suppose to be
cases of progressive change m races, it is not that they are iso-
lated cases or exceptionally appropriate; for innumerable
similar ones might be adduced. In the course of the detailed
examination I have tiad successively to make of the floras of
Europe, N. W. America, Tropical America, Tropical Africa,
China, and Australia, I have everywhere observed that com-
munity of general type, in regions now dissevered, is, when
once varied, accompanied by more or less of divei^ence in
more special characters in different directions in the different
countnea

With regard to tiie succession of races which have undergone
a complete specific change through successive geological periods,
we have not in plants, as fiu* as I am aware, any such cases of
"true linear types or forms which are intermediate between
others because they stand in a direct genetic relation to them,"
as Professor Huxley appears to have made out in fiivor of the

gjdigree of the Horse m his last Anniversary Address to the
eological Society. And I may, in r^ard to plants, repeat witii



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Extra/cts from Mr. BentharrCs Address. ^ &81

still greater emphasis his dictum, that " it is no easy matter to find
clear and unmistakable evidence of filiation among fossil animals ;
for in order that such evidence should bo (juite satisfactory, it is
necessary that we should be acquainted with all the most im-
portant features of the organization of the animals which are
supppsed to be thus related, and not merely with the fragments
upon which the genera and species of the paleontologist are so
often based." The difficulty is much greater in the case of
fossil plants; for instead of bones, teeth, or shells, portions of
internal or external skeletons, the parts preserved to us from
the tertiary period are generally those least indicative of struc-
tural organization. Mr. Carruthers has recently (Geological
Magazine, April and July 1869, and Journal of the Geological
Society, August, 1869) adduced satisfactory evidence oi the
close affinity of Siffillaria and the allied genera of the coal-
period with the living Lycopodiaceae, formerly suggested by
Dt, Hooker; but, as he informs me, no connecting links, no
specimens, indeed, of the whole Order, have as yet been found
in any of the intermediate cretaceous or tertiary deposits.
Among the latter, the presence of numerous vegetable types,
to which we mav plausibly refer as to the ancestors of living
races, is establishea upon unimpeachable data ; bi^it I have been
unable to find that a single case of authentic pedigree, as suc-
cessively altered from the cretaceous through tne abundant de-
posits of the eocene and miocene period to the living races, has
oeen as yet as satisfectorily made out as that of the absolute
identity of Taocodium and others above mentioned, although I
feel very little doubt that such a one will yet be traced when
our paleontologists shall have ceased to confound and reason
alike upon the best proved facts and the wildest guesses. Our
late distinguished foreign Member, Professor Unger, whose loss
we have so recently to deplore, had indeed, shortly before his
death, published, under the name of 'Geoloffie der europaischen
Waldbaume, part 1, Laubholzer,' no less than twelve tabular
pedigrees of European forest races ; but it seems to me that in
this, as in another of the same eminent paleontologist's papers
to which I shall presently have to refer, his speculations have
been deduced much more freely from conjectures than from
facts. There is no doubt that the presence of closely allied
representatives of our Beeches, Birches, Alders, Oaks, Limes,
&C., in the tertiary deposits of Central and Southern Europe is
fully proved by inflorescences and fruits as well as leaves ; but
how can we establish the successive changes of character in a
race when we have only the inflorescence of one period, the
fruit of another, and the leaf of a third? I do not find a
single case in which all three have been found in more than one
stage ; and by far the great majority of these fossil species are



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882 Extracts from Mr. BenOiarns Address.

established on the authority of detached leaves or jfragments of
leaves alona

Now let us consider for a moment what place a leaf really
holds in systematic botany. Would any experienced system-
atic botanist, however acute, on the sole examination of an un-
known lea^ presume to determine, not only its natural order
and genus, but its precise characters as an unpublished species?
It is true that monographists have sometimes published new
species founded on specimens without flower or fruit, which
ttom collateral circumstances of habitat, collector's notes, gene-
ral resemblance, &c., they had good reason to believe really be-
longed to the genus they were occupied vdth ; but then they
had the advantage of ascertaining the general fades derived
from insertion, relative position, presence or absence of stipular
appendages, &c., besides the data supplied by the branch itself
And with all these aids, even the elder De C^doUe, than whom
no botanist was more sagacious in judging of a genus from
general aspect, proved to have been in several instances fiar
wrong in tne ffenus, and even Order, to which he had attributed
species descrioed from leaf-specimens only. Paleontologists,
on the other hand, have, in the majority of these tertiary de-
posits, had nothing to work upon but detached leaves or frag-
ments of leaves, exhibiting only outward form, venation, and,
to a certain deffree, epidermal structure, all of which characters
may be referred to that class which Professor Flower, in his in-
troductory lecture at the Royal CoU^e of Sui^geons in Febru-
ary last, has so aptly designated as aaaptive, in contradistinction
to essential and fondamental characters. They may, when
taken in conjunction with relative individual abundance, assist
in forming a general idea of the aspect of vegetation, and thus
give some clue to certain physical conditions of the country ;
but they alone can afford no indication of genetic affinity, or
consequently of origin or successive geographical distribution.

Lesquereux, in speaking of Cretaceous "species, or rather
forms of leaves," ofeerves, in a note to his paper on Fossil
Plants from Nebraska (this Journal, voL xlvi, July, 1868, p.
108), that "it is well imderstood that when the wora spates is
used in an examination of fossil plants, it is not taken in its

1)recise8ense; for indeed no smecies can be established from
eaves or mere fragments of leaves. But as paleontologists
have to recognize these forms described and figured, to com-

8 are them and use them for reference, it is necessary to affix to
lem specific names, and therefore to consider them as species."
But the investigators of the tertiary floras of Central and South-
em Europe have accjuired the habit, not only of neglecting this
distinction and naming and treating these forms of leaves as
species equivalent to those established on living plants, but of



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Extracts from Mr. BerUham^s Andreas. 888

founding upon them theories which must fell to the ground if
such specific determination proves inaccurate. Nothing can be
more satisfactory than such determinations as that of Podogo-
ntumj for instance, which Professor Heer has succeeded in
proving, by numerous specimens of leaves, firuits, and even
flowers, some of them stul attached to the branches, which I
had myself the pleasure of inspecting last summer under the
fiiendly guidance of the* distinguished Professor himself This
genus of CsBsalpinieae, from its evident affinity with PeUogyne^
Tamarindus^ and others now scattered over the warmer regions
of America and AMca, and more sparingly in Asia, tells a tale
of much significance as to the physico-geographical relations of



Online LibraryRodolfo Amedeo LancianiThe American journal of science and arts → online text (page 91 of 109)