F373    Book:     Darwin, C. R. 1859. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 1st ed., 1st issue.   Text   Image   PDF

the changes of climate and of the level of the land, which have certainly occurred within the recent period, and of other similar changes which may have occurred within the same period; if we remember how profoundly ignorant we are with respect to the many and curious means of occasional transport,—a subject which has hardly ever been properly experimentised on; if we bear in mind how often a species may have ranged continuously over a wide area, and then have become extinct in the

F373    Book:     Darwin, C. R. 1859. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 1st ed., 1st issue.   Text   Image   PDF

occasional means of transport. With respect to distinct species of the same genus inhabiting very distant and isolated regions, as the process of modification has necessarily been slow, all the means of migration will have been possible during a very long period; and consequently the difficulty of the wide diffusion of species of the same genus is in some degree lessened. As on the theory of natural selection an interminable number of intermediate forms must have existed, linking together all the

F373    Book:     Darwin, C. R. 1859. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 1st ed., 1st issue.   Text   Image   PDF

of the islands would have been formed, like other mountain-summits, of granite, metamorphic schists, old fossiliferous or other such rocks, instead of consisting of mere piles of volcanic matter. I must now say a few words on what are called accidental means, but which more properly might be called occasional means of distribution. I shall here confine myself to plants. In botanical works, this or that plant is stated to be ill adapted for wide dissemination; but for transport across the sea

F373    Book:     Darwin, C. R. 1859. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 1st ed., 1st issue.   Text   Image   PDF

fish, I believe that the same species never occur in the fresh waters of distant continents. But on the same continent the species often range widely and almost capriciously; for two river-systems will have some fish in common and some different. A few facts seem to favour the possibility of their occasional transport by accidental means; like that of the live fish not rarely dropped by whirlwinds in India, and the vitality of their ova when removed from the water. But I am inclined to

F373    Book:     Darwin, C. R. 1859. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 1st ed., 1st issue.   Text   Image   PDF

points of the earth's surface, can in many instances be explained on the view of each species having migrated from a single birthplace; then, considering our ignorance with respect to former climatal and geographical changes and various occasional means of transport, the belief that this has been the universal law, seems to me incomparably the safest. In discussing this subject, we shall be enabled at the same time to consider a point equally important for us, namely, whether the several distinct

F373    Book:     Darwin, C. R. 1859. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 1st ed., 1st issue.   Text   Image   PDF

fairly be attributed to our not having as yet discovered in an intermediate deposit the forms which are therein absent, but which occur above and below: so in space, it certainly is the general rule that the area inhabited by a single species, or by a group of species, is continuous; and the exceptions, which are not rare, may, as I have attempted to show, be accounted for by migration at some former period under different conditions or by occasional means of transport, and by the species

F376    Book:     Darwin, C. R. 1860. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 2d ed., second issue.   Text   Image   PDF

seeds do not retain their vitality when exposed for a great length of time to the action of sea-water; nor could they be long carried in the crops or intestines of birds. These means, however, would suffice for occasional transport across tracts of sea some hundred miles in breadth, or from island to island, or from a continent to a neighbouring island, but not from one distant continent to another. The floras of distant continents would not by such means become mingled in any great degree; but

F376    Book:     Darwin, C. R. 1860. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 2d ed., second issue.   Text   Image   PDF

(and it would be very difficult to prove this), received within the last few centuries, through occasional means of transport, immigrants from Europe or any other continent, that a poorly-stocked island, though standing more remote from the mainland, would not receive colonists by similar means. I do not doubt that out of twenty seeds or animals transported to an island, even if far less well-stocked than Britain, scarcely more than one would be so well fitted to its new home, as to become

F376    Book:     Darwin, C. R. 1860. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 2d ed., second issue.   Text   Image   PDF

many occasional means of transport. With respect to distinct species of the same genus inhabiting very distant and isolated regions, as the process of modification has necessarily been slow, all the means of migration will have been possible during a very long period; and consequently the difficulty of the wide diffusion of species of the same genus is in some degree lessened. As on the theory of natural selection an interminable number of intermediate forms must have existed, linking together all

F380    Book:     Darwin, C. R. 1860. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. New York: D. Appleton. New edition, revised and augmented.   Text   Image   PDF

chance be of a seed falling on favourable soil, and coming maturity?. But it would be a great error to argue that because a well-stocked island, like eat Britain, has not, as far as is known (and it would be very difficult to prove this), received within the last few centuries, through occasional means of transport, immigrants from Europe or any other continent,. that a poorly-stocked island, though standing more remote from the mainland, would not receive colonists by similar means. I do not

F376    Book:     Darwin, C. R. 1860. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 2d ed., second issue.   Text   Image   PDF

and isolated flora. I suspect that before this flora was exterminated by the Glacial epoch, a few forms were widely dispersed to various points of the southern hemisphere by occasional means of transport, and by the aid, as halting-places, of existing and now sunken islands. By these means, as I believe, the southern shores of America, Australia, New Zealand, have become slightly tinted by the same peculiar forms of vegetable life. Sir C. Lyell in a striking passage has speculated, in language

F376    Book:     Darwin, C. R. 1860. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 2d ed., second issue.   Text   Image   PDF

occasional means of transport having been largely efficient in the long course of time, than with the view of all our oceanic islands having been formerly connected by continuous land with the nearest continent; for on this latter view the migration would probably have been more complete; and if modification be admitted, all the forms of life would have been more [page] 39

F376    Book:     Darwin, C. R. 1860. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 2d ed., second issue.   Text   Image   PDF

those of Africa, like those of the Galapagos to America. I believe this grand fact can receive no sort of explanation on the ordinary view of independent creation; whereas on the view here maintained, it is obvious that the Galapagos Islands would be likely to receive colonists, whether by occasional means of transport or by formerly continuous land, from America; and the Cape de Verde Islands from Africa; and that such colonists would be liable to modification;—the principle of inheritance

F376    Book:     Darwin, C. R. 1860. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 2d ed., second issue.   Text   Image   PDF

endemic species, which cannot be here fairly included, as we are considering how they have come to be modified since their arrival), we find a considerable amount of difference in the several islands. This difference might indeed have been expected on the view of the islands having been stocked by occasional means of transport—a seed, for instance, of one plant having been brought to one island, and that of another plant to another island. Hence when in former times an immigrant settled on any

F380    Book:     Darwin, C. R. 1860. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. New York: D. Appleton. New edition, revised and augmented.   Text   Image   PDF

distinct species have migrated in radiating lines from some common centre; and I am inclined to look in the southern, as in the northern hemisphere, to a former and warmer period, before the commencement of the Glacial period, when the antarctic lands, now covered with ice, supported a highly peculiar and isolated flora. I suspect that before this flora was exterminated by the Glacial epoch, a few forms were widely dispersed to various points of the southern hemisphere by occasional means of transport

F380    Book:     Darwin, C. R. 1860. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. New York: D. Appleton. New edition, revised and augmented.   Text   Image   PDF

Glacial period on the distribution both of the same and of representative species throughout the world. We are as yet profoundly ignorant of the many occasional means of transport. With respect to distinct species of the same genus inhabiting very distant and isolated regions, as the process of modification has necessarily been slow, all the means of migration will have been possible during a very long period; and consequently the difficulty of the wide diffusion of species of the same genus

F380    Book:     Darwin, C. R. 1860. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. New York: D. Appleton. New edition, revised and augmented.   Text   Image   PDF

climatal and geographical changes and various occasional means of transport, the belief that this has been the universal law, seems to me incomparably the safest. In discussing this subject, we shall be enabled at the same time to consider a point equally important for us, namely, whether the several distinct species of a genus, which on my theory have all descended from a common progenitor, can have migrated (undergoing modification during some part of their migration) from the area inhabited by

F380    Book:     Darwin, C. R. 1860. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. New York: D. Appleton. New edition, revised and augmented.   Text   Image   PDF

Verde Islands are related to those of Africa, like those of the Galapagos to America. I believe this grand fact can receive no sort of explanation on the ordinary view of independent creation; whereas on the view here maintained, it is obvious that the Galapagos Islands would be likely to receive colonists, whether by occasional means of transport or by formerly continuous land, from America; and the Cape de Verde Islands from Africa; and that such colonists would be liable to modification; the

F1706    Periodical contribution:     Darwin, C. R. 1860. Fertilisation of British orchids by insect agency. Gardeners' Chronicle and Agricultural Gazette no. 23 (9 June): 528.   Text   Image   PDF

years or in some other districts, insects do visit the Bee Orchis and occasionally transport pollen from one flower to another, and thus give it the advantage of an occasional cross. We have seen that the Fly Orchis is not in this part of the country by any means sufficiently often visited by insects, though the visits of insects are indispensable to its fertilisation. So with the Bee Orchis, though its self-fertilisation is specially provided for, it may not exist here under the most favourable

F381    Book:     Darwin, C. R. 1861. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 3d ed. Seventh thousand.   Text   Image   PDF

similar means. Out of twenty seeds or animals transported to an island, even if far less well-stocked than Britain, perhaps not more than one would be so well fitted to its new home, as to become naturalised. But this, as it seems to me, is no valid argument against what would be effected by occasional means of transport, during the long lapse of geological time, whilst an island was being upheaved, and before it had become fully stocked with inhabitants. On almost bare land, with few or no

F381    Book:     Darwin, C. R. 1861. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 3d ed. Seventh thousand.   Text   Image   PDF

difficulties are insuperable; though they often are in this case, and in that of the individuals of the same species, extremely great. As exemplifying the effects of climatal changes on distribution, I have attempted to show how important has been the influence of the modern Glacial period, which I am fully convinced simultaneously affected the whole world, or at least great longitudinal belts. As showing how diversified are the means of occasional transport, I have discussed at some little

F381    Book:     Darwin, C. R. 1861. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 3d ed. Seventh thousand.   Text   Image   PDF

We can here consider only a few cases. In regard to fish, I believe that the same species never occur in the fresh waters of distant continents. But on the same continent the species often range widely and almost capriciously; for two river-systems will have some fish in common and some different. A few facts seem to favour the possibility of their occasional transport by accidental means; like that of the live fish not rarely dropped by whirlwinds in India, and the vitality of their ova when

F381    Book:     Darwin, C. R. 1861. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 3d ed. Seventh thousand.   Text   Image   PDF

occasional means of transport having been largely efficient in the long course of time, than with the view of all our oceanic islands having been formerly connected by continuous land with the nearest continent; for on this latter view the migration would probably have been more complete; and if modification [page] 42

F381    Book:     Darwin, C. R. 1861. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 3d ed. Seventh thousand.   Text   Image   PDF

species on islands and on the mainland, though separated by hundreds of miles of open sea. If the existence of the same species at distant and isolated points of the earth's surface, can in many instances be explained on the view of each species having migrated from a single birthplace; then, considering our ignorance with respect to former climatal and geographical changes and various occasional means of transport, the belief that this has been the universal law, seems to me incomparably the

F381    Book:     Darwin, C. R. 1861. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 3d ed. Seventh thousand.   Text   Image   PDF

several islands. This difference might indeed have been expected on the view of the islands having been stocked by occasional means of transport—a seed, for instance, of one plant having been brought to one island, and that of another plant, to another island. Hence when in former times an immigrant settled on any one or more of the islands, or when it subsequently spread from one island to another, it would undoubtedly be exposed to different conditions of life in the different islands, for it