304 
NATURE 
[ Fan. 25, 1883 
reproduction has taken place in their ancestry being at the same 
time reduced to a minimum, 
On the contrary, we must expect that a much smaller number 
of ancestors lies between the lower-developed groups and the 
common parent form, that a-sexual reproduction has here more 
repeatedly occurred, and that finally, Darwin’s and Huxley’s 
explanation, which we have above alluded to, of the non-occurrence 
of further modifications, may here have been realised to a greater 
extent. 
Keeping in view the combined action of both these principles, 
we no longer wonder that even in the present day living repre- 
sentatives are found of genera which were already present in the 
Silurian epoch, nor that the simplest organised beings have con- 
tinued to exist in that primitive form. 
They are for the greater part the younger sons, and being con- 
demned to a slower rate of development, they could not keep 
apace of their elder brothers. The latter, which have so much 
oftener passed through the improving crucible of sexual repro- 
duction, are indebted to that cause for having become the parent 
stock out of which the higher and highest-developed animal and 
vegetable forms, now surrounding us, have gradually sprung. 
THE ETHER AND ITS FUNCTIONS} 
I HOPE that no one has been misled by an error in the printing 
of the title of this lecture, viz. the omission of the definite 
article before the word ether, into supposing that I am going to 
discourse on chemistry and the latest anesthetic ; you will have 
understood, I hope, that ‘‘ether” meant ¢#e ether, and that the 
ether is the hypothetical medium which is supposed to fill other- 
wise empty space. 
The idea of an ether is by no means a new one, As soon as 
a notion of the enormous extent of space had been grasped, by 
means of astronomical discoveries, the question presented itself 
to men’s minds, what was in this space? was it full, or was it 
empty? and the question was differently answered by different 
metaphysicians, Some felt that a vacuum was so abhorrent a 
thing that it could not by any possibility exist anywhere, but 
that nature would not be satisfied unless space were perfectly 
full. Others, again, felt that ety space could hardly exist, 
that it would shrink up to nothing like a pricked bladder unless 
it were kept distended by something material. In other words, 
they made matter the condition of extension. On the other hand, 
it was contended that however objectionable the idea of empty 
space might be, yet emptiness was a necessity in order that 
bodies might have room to move; that, in fact, if all space were 
perfectly full of matter everything would be jammed together, 
and nothing like free attraction or free motion of bodies round 
one another could go on. 
And indeed there are not wanting philosophers at the present 
day who still believe something of this same kind, who are satis- 
fied to think of matter as consisting of detached small particles 
acting on one another with forces varying as some inverse power 
of the distance, and who, if they can account for a phenomenon 
by an action exerted across empty space, are content to go no 
further, nor seek the cause and nature of the action more 
closely.7 
Now metaphysical arguments, in so far as thay have any 
weight or validity whatever, are unconscious appeals to experi- 
ence ; a person endeavours to find out whether a certain condi- 
tion of things is by him conceivable, and if it is not conceivable 
he has some grima facie ground for asserting that it probably 
does not exist, Isay he has some ground, but whether it be 
much or little depends partly on the nature of the thing thought 
of, whether it be fairly simple or highly complex, and partly on 
the range of the man’s own mental development, whether his 
experience be wide or narrow. 
If a highly-developed mind, or set of minds, find a doctrine 
about some comparatively simple and fundamental matter abso- 
lutely unthinkable, it is an evidence, and it is accepted as good 
evidence, that the unthinkable state of things is one that has no 
existence ; the argument being that if it did exist, either it or 
something not wholly unlike it would have come within the 
range of experience. We have no further evidence than this for 
the statement that two straight lines cannot inclose a space, or 
that the three angles of a triangle are equal to two right angles. 
£ ee by Prof. Oliver Lodge at the London Institution, on December 
2 1052, 
2 Tn illustration of this statement an article has since appeared in the 
January number of the Philosophical Magazine, by Mr. Walter Browne. 
Nevertheless there is nothing final about suck an argument ; all 
that the inconceivability of a thing really proves, or can prove, 
is that nothing like it has ever come within the thinker’s expe- 
rience; and this proves nothing as to the reality or non-reality 
of the thing, unless his experience of the same kind of things 
has been so extensive as to make it reasonably probable that if 
such a thing had existed it would not have been so completely 
overlooked. 
The experience of a child or a dog, on ordinary scientific 
phenomena, therefore, is worth next to nothing; and as the 
experience of a dog is to ordinary science, so is the experience 
of the human race to some higher phenomena, of which they at 
present know nothing, and against the existence of which it is 
perfectly futile and presumptuous to bring forward arguments 
about their being inconceivable, as if they were likely to be any- 
thing else. 
Now if there is one thing with which the human race has 
been more conyersant from time immemorial than another, and 
concerning which more experience has been unconsciously 
accumulated than about almost anything else that can be men- 
tioned, it is the action of one body on another ; the exertion of 
force by one body upon another, the transfer of motion and energy 
from one body to another; any kind of effect, no matter what, 
which can be produced in one body by means of another, whether 
the bodies be animate or inanimate. The action of a man in 
felling a tree, in thrusting a spear, in drawing a bow ; the action 
of the bow again on the arrow, of powder on a bullet, of a horse 
on a cart ; and again, the action of the earth on the moon, or of 
a magnet on iron. Every activity of every kind that we are 
conscious of may be taken as an illustration of the action of one 
body on another. 
Now I wish to appeal to this mass of experience, and to ask, 
is not the direct action of one body on another across empty 
space, and with no means of communication whatever, is not this 
absolutely unthinkable? We must not answer the question off- 
hand, but must give it due consideration, and we shall find, I 
think, that wherever one body acts on another by obvious 
contact, we are satisfied and have a feeling that the phenomenon 
is simple and intelligible ; but that whenever one body apparently 
acts on another at a distance, we are irresistibly impelled to 
look for the connecting medium. 
If a marionette dances in obedience to a prompting hand 
above it, any intelligent child would feel for the wire, and if no 
wire or anything corresponding to it were discovered, would 
feel that there was something uncanny and magical about the 
whole thing. Ancient attempts at magic were indeed attempts to _ 
obtain results without the trouble of properly causing them, to 
build palaces by rubbing rings or lanterns, to remove mountains 
by a wich instead of with the spade and pickaxe, and generally 
to act on bodies without any real means of communication ; and 
modern disbelief in magic is simply a statement of the conviction 
of mankind that all attempts in this direction have turned out 
failures, and that action at a distance is impossible. 
If aman explained the action of a horse or a cart by saying 
that there was an attraction between them varying as some high 
direct power of the distance, he would not be saying other than 
the truth—the facts may be so expressed—but he would be felt 
to be giving a wretchedly lame explanation, and any one who 
simply pointed out the traces would be going much more to the 
root of the matter. Similarly with the attraction of a magnet 
for another magnetic pole. ‘To say that there is an attraction as 
the inverse cube of the distance between them is true, but it is 
not the whole truth ; and we should be obliged to any one who 
will point out the traces, for traces we feel sure there are. If 
any one tries to picture clearly to himself the action of one body 
on another without any medium of communication whatever, he 
must fail. A medium is instinctively looked for in most cases, 
and if not in all, as in falling weights or in magnetic attraction, 
it is only because custom has made us stupidly callous to the real 
nature of these forces. 
When we see a vehicle bowling down-hill without any visible 
propelling force we ought to regard it with the same mixture 
of curiosity and wonder as the Chinaman felt when he saw for 
the first time in the streets of Philadelphia a tram-car driven by 
a rope buried in a pipe underground. The attachment to these 
cars comes through a narrow slit in the pipe, and is quite unob- 
trusive. After regarding the car with open-mouthed astonish- 
ment for some time, the Chinaman made use of the following 
memorable exclamation, ‘‘No pushee—No pullee—Go like 
mad!” He was a philosophic Chinaman, 
