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lectures on evolution-第14章

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to be informed; what is the foundation for the statement that

evolution does require so great a time? The biologist knows

nothing whatever of the amount of time which may be required for

the process of evolution。 It is a matter of fact that the equine

forms which I have described to you occur; in the order stated;

in the Tertiary formations。 But I have not the slightest means

of guessing whether it took a million of years; or ten millions;

or a hundred millions; or a thousand millions of years; to give

rise to that series of changes。 A biologist has no means of

arriving at any conclusion as to the amount of time which may be

needed for a certain quantity of organic change。 He takes his

time from the geologist。 The geologist; considering the rate at

which deposits are formed and the rate at which denudation goes

on upon the surface of the earth; arrives at more or less

justifiable conclusions as to the time which is required for the

deposit of a certain thickness of rocks; and if he tells me that

the Tertiary formations required 500;000;000 years for their

deposit; I suppose he has good ground for what he says; and I

take that as a measure of the duration of the evolution of the

horse from the Orohippus up to its present condition。

And; if he is right; undoubtedly evolution is a very slow

process; and requires a great deal of time。 But suppose; now;

that an astronomer or a physicistfor instance; my friend Sir

William Thomsontells me that my geological authority is quite

wrong; and that he has weighty evidence to show that life could

not possibly have existed upon the surface of the earth

500;000;000 years ago; because the earth would have then been

too hot to allow of life; my reply is: 〃That is not my affair;

settle that with the geologist; and when you have come to an

agreement among yourselves I will adopt your conclusion。〃

We take our time from the geologists and physicists; and it is

monstrous that; having taken our time from the physical

philosopher's clock; the physical philosopher should turn round

upon us; and say we are too fast or too slow。 What we desire to

know is; is it a fact that evolution took place? As to the

amount of time which evolution may have occupied; we are in the

hands of the physicist and the astronomer; whose business it is

to deal with those questions。



I have now; ladies and gentlemen; arrived at the conclusion of

the task which I set before myself when I undertook to deliver

these lectures。 My purpose has been; not to enable those among

you who have paid no attention to these subjects before; to

leave this room in a condition to decide upon the validity or

the invalidity of the hypothesis of evolution; but I have

desired to put before you the principles upon which all

hypotheses respecting the history of Nature must be judged;

and furthermore; to make apparent the nature of the evidence and

the amount of cogency which is to be expected and may be

obtained from it。 To this end; I have not hesitated to regard

you as genuine students and persons desirous of knowing the

truth。 I have not shrunk from taking you through long

discussions; that I fear may have sometimes tried your patience;

and I have inflicted upon you details which were indispensable;

but which may well have been wearisome。 But I shall rejoiceI

shall consider that I have done you the greatest service which

it was in my power to doif I have thus convinced you that the

great question which we have been discussing is not one to be

dealt with by rhetorical flourishes; or by loose and superficial

talk; but that it requires the keen attention of the trained

intellect and the patience of the accurate observer。



When I commenced this series of lectures; I did not think it

necessary to preface them with a prologue; such as might be

expected from a stranger and a foreigner; for during my brief

stay in your country; I have found it very hard to believe that

a stranger could be possessed of so many friends; and almost

harder that a foreigner could express himself in your language

in such a way as to be; to all appearance; so readily

intelligible。 So far as I can judge; that most intelligent; and

perhaps; I may add; most singularly active and enterprising

body; your press reporters; do not seem to have been deterred by

my accent from giving the fullest account of everything that I

happen to have said。



But the vessel in which I take my departure to…morrow morning is

even now ready to slip her moorings; I awake from my delusion

that I am other than a stranger and a foreigner。 I am ready to

go back to my place and country; but; before doing so; let me;

by way of epilogue; tender to you my most hearty thanks for the

kind and cordial reception which you have accorded to me;

and let me thank you still more for that which is the greatest

compliment which can be afforded to any person in my position

the continuous and undisturbed attention which you have bestowed

upon the long argument which I have had the honour to lay

before you。





FOOTNOTES



(1) The absence of any keel on the breast…bone and some other

osteological peculiarities; observed by Professor Marsh;

however; suggest that Hesperornis may be a modification

of a less specialised group of birds than that to which these

existing aquatic birds belong。



(2) A second specimen; discovered in 1877; and at present in the

Berlin museum; shows an excellently preserved skull with teeth;

and three digits; all terminated by claws; in the fore limb。

1893。



(3)I use the word 〃type〃 because it is highly probable that many

forms of Anchitherium…like and Hipparion…like

animals existed in the Miocene and Pliocene epochs; just as many

species of the horse tribe exist now; and it is highly

improbable that the particular species of Anchitherium or

Hipparion; which happen to have been discovered; should

be precisely those which have formed part of the direct line of

the horse's pedigree。



(4) Since this lecture was delivered; Professor Marsh has

discovered a new genus of equine mammals (Eohippus) from

the lowest Eocene deposits of the West; which corresponds very

nearly to this description。American Journal of Science;

November; 1876。











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