PREFACE
PREFACE
Although this volume contains a great amount of original
material, I am largely indebted to the labours of my predecessors
for its present form; and a scheme that at first was limited
only to my own observations in the Pacific has gradually extended
itself to the general subject of plant-dispersal. The
farther I proceeded in my work the more I realised that the
floras of the Pacific islands are of most interest in their connections,
and that the problems affecting them are problems
concerning the whole plant-world. Deprived of the writings
of Seemann, Hillebrand, Drake del Castillo, and other botanists,
several of whom have lived and died in the midst of their
studies of these floras, and without the aid of the works of
Hemsley and Schimper, generalisers who have mainly cleared
the way for the systematic study of plant-distribution and
plant-dispersal, it would not have been possible for me to accomplish
such an undertaking.
My interest in plant-dispersal dates back to 1884, when,
whilst surgeon of H.M.S. Lark, in the Solomon Islands, I made
some observations on the stocking of a coral island with its
plants, which were published in the Report on the Botany of
the “Challenger” Expedition. In 1888 I followed up the same
line of investigation during a sojourn of three months on
Keeling Atoll, and during a journey along the coasts of West
Java. But realising that as yet I had barely touched the
fringe of a great subject, and that several years of study would
be required before one could venture even to appreciate the
nature of the problems involved and much less to weigh results,
viiiI took advantage of the circumstances of my life to make,
between the years 1890 and 1896, a prolonged investigation of
the plants of the British flora, mainly from the standpoint of
dispersal by water. This involved the study of the seed-drift
of ponds and rivers and of the plants supplying it, a study
which brought me into close relation with aquatic and sub-aquatic
plants. This line of investigation led me into contact
with many other aspects of plant-life; and as time went on
my field of interest extended to the plants of dry stations and
to the bird as an agent in plant-dispersal. Only a few of these
results have been published, as in the journals of the Linnean
Society and of the Royal Physical Society of Edinburgh as well as
in the pages of Science Gossip. They lie for the most part still
within my note-books, and fitly so, since I regarded such studies
chiefly as a preparation for the investigation of the general
question of plant-dispersal.
When again, in October, 1896, I found myself once more in
the Pacific, the subject was taken up again with zeal; but my
larger experience had only increased my diffidence, and the
unknown looked so overwhelming that I settled down for the
next three years content with merely making experiments and
recording observations. Here again the main problem was
attacked through the study of seed-buoyancy, and gradually
it led me to the systematic study of the mangroves and of the
beach-plants, whilst my inland excursions brought me into
familiarity with the plants of the interior. My geological
exploration of the island of Vanua Levu, in Fiji, greatly
assisted me by giving a method to my botanical examination
of the island.
Whilst working out my geological collections in England, in
the years 1900-1902, I devoted an hour or two daily to the
elaboration of my botanical notes and to a consideration of
the problems concerned. During a winter in Sicily I took up
again the subject of the beach-plants; and after the publication
of the volume on the geology of Vanua Levu I was able
to accomplish a plan, for years in my dreams, of visiting the
eastern shores of the Pacific. During a period of three months
ixfrom December, 1903, to March, 1904, I examined the littoral
flora of the west side of South America at various localities
between Southern Chile and Ecuador; and finally completed
this investigation by comparing the shore-plants on the Pacific
and Atlantic coasts of the isthmus of Panama. Returning to
England with a fresh collection of data, I passed many months
in elaborating and arranging all my notes, waiting vainly for a
clue to guide me in framing a scheme by which I could bring
the results of many years of work into some connected form.
At last I decided once again to take the floating seed as my
clue, and without any prearranged plan I allowed the work to
evolve itself. Now that it is finished, I can see some obvious
defects; but if any other plan had been adopted I scarcely
think that I should have been more successful in piecing
together in a single argument materials resulting from so
many years of research and relating to so many aspects of
plant-life.
Yet the final object of a naturalist would be but a sorry one,
if his aim were only to write a treatise and append his name to it.
His personal faith lies behind all his work; and no one can pursue
a long line of study of the world around him without rising from
his task with some convictions gained and some convictions lost.
As far as the observation of Nature’s processes at present in
operation can guide us, the world presents itself to us only as a
differentiating world. We can perceive, it is true, a progressive
arrangement of types of organisms from the lowest to the highest,
and we can perceive a development of varieties of the several
types; but the only process evident to our observation is that
concerned with the production of varieties of the type. Nature
does not enlighten us as to the mode of development of the type
itself. We can, for instance, detect in actual operation the process
by which the different kinds of bats or the different kinds of men
have been developed; but there is no principle in Nature evident
to our senses that is concerned with type-creation. Though we
can supply it by hypothesis, we cannot discover it in fact. On the
other hand, the evidence of differentiation is abundant on all sides
of us, both in the organic and in the inorganic worlds. The history
xof the globe has ever proceeded from the uniform to the complex;
and in the closing chapter of this book an endeavour is made to
connect the differentiation of plant and bird with the differentiation
of the conditions of existence on the earth. But this leaves no
room for the development of new types of organisms; and so far
as observation of the processes of Nature at present working around
us can guide us, each type might well be regarded as eternal. We
can never hope to arrive at an explanation of the progressive
development of types by studying the differentiating process;
and since the last is alone cognisable for us, evolution, as it is
usually termed, becomes an article of our faith, and of faith only.
In illustration of this argument, let me take the case of the
races of men. We see mankind in our own day illustrating the
law of differentiation all over the globe, as far as physical characters
are concerned. Just as the ornithologist would postulate a
generalised type in tracing the origin of various allied groups of
birds, so the anthropologist, guided by his observation of the
changes now offered by man in different regions, would postulate
a generalised original type as the parent-stock of mankind.
Observation of the processes of change now in operation by no
means leads us to infer that such a generalised type was an
anthropoid ape, or even simian in character. In so doing we
should be forming a conclusion not warranted by the observation
of existing agencies of change, and we should be confusing the
two distinct processes of evolution and differentiation, or rather
of progressive and divergent evolution, of which the last alone
comes within our field of cognition. The study of variation can
do no more than enable us to ascertain the mode of development
of different kinds, we will say, of birds or of men. The origin of
the type lies outside our observation. “Given the type, to explain
its origin”: this is the problem we can never solve, and Nature
aids us nothing by the study of her ways. On the other hand,
there is the subsidiary problem.... “Given a type, to explain its
varieties” ...; and here Nature’s processes are apparent to us in
a thousand different shapes.
It might seem that the presumptive evidence connecting man
in his origin with the monkeys is so strong that, supposing his
xisimian descent were regarded as a crime, a jury would without
hesitation pronounce his guilt; but until some observer of the
processes followed by Nature can bridge over the gap that divides
man from the ape, until indeed he can offer a legitimate illustration
of how it is accomplished in similar cases in our own day, the gap
remains. Those who have read the recent work of Prof. Metchnikoff
on the Nature of Man will properly regard his chapter on the
simian origin of man as a brilliant argument advanced by a most
competent authority. Yet he fails to complete his case by bridging
over this gap, and can only appeal to the results of the now
famous researches of De Vries concerning the mutations of the
evening primrose (Œnothera). It is probable, he says, that man
owes his origin to a similar phenomenon (English edition, p. 57).
Several objections could be raised against this illustration from
the plant-world, the most important of them lying in the circumstance
that these mutations could only be urged as instances of
the sudden development of new species of the evening primrose
type. They merely illustrate the process of differentiation from
a given type, and by no means represent the process of progressive
evolution from a simian to a man.
However, look where we may—and this is the great lesson I
have learned from my researches in the Pacific islands—Nature
does not present to our observation any process in operation by
which a new type of organism is produced. The processes involved
lie hidden from our view. The channels by which impressions
from the outside world reach us are comparatively few; and
although it seems likely that the future development of man will
be mainly concerned with the acquirement of additional sense-channels,
no newly acquired sense will enable him to be at once
an actor in and a spectator of the great drama presented in the
organic world. That a creature should be able to get at the back
of its own existence, or, in other words, to penetrate the secret of
its own creation, is unthinkable. Outside the limited field of
observation that immediately surrounds us extends the region
where reason alone can guide us, and beyond lies the realm where
reason fails and faith begins.
H. B. GUPPY.
November 8th, 1905.