June 1, 1899] 
NADORE 
103 
ON SOME RECENT ADVANCES IN SPECTRUM 
ANALYSIS RELATING TO INORGANIC AND 
ORGANIC EVOLUTION} 
N the last lecture I dealt with that new development 
of spectrum analysis which has enabled us to dis- 
cuss, with greater fulness*than was possible before, the 
various chemical conditionings in the different regions of 
our system as marked out for us by the Milky Way. I 
now have to refer to another development in a somewhat 
different direction. We have, as I think you will agree, 
by the discussion of the relation of the celestial bodies 
of all sorts to the Milky Way, demonstrated that the 
evolution of the cosmos in all probability took place from 
the gradual condensation of swarms of meteorites ; and 
that such swarms are still more numerous there, and 
give rise to the new stars, bright-line stars and variable 
stars which are most numerous in its plane. When this 
work was begun our knowledge was so incomplete that a 
continuous chain of chemical facts was out of the ques- 
tion ; but, thanks to the advances to which I have now 
to refer, we can deal with this cosmical evolution from a 
chemical standpoint, and what we have to do to-night is 
to consider the result of this inquiry. 
I may begin by saying that now the gaps in our know- 
ledge have been filled up, we find ourselves in the pre- 
sence of a chemical evolution which is really majestic in 
its simplicity. Such a chemical evolution was suggested 
by me many years ago now, to explain the few stellar 
facts with which we were then familiar ; but I do not pro- 
pose to take up your time with any historical allusions ; 
1 must point out, however, that we to-night are in a very 
much better condition to consider this problem than we 
have ever been before, because at the present moment we 
have tens of thousands, | might almost say hundreds of 
thousands, of coordinated facts to go upon. 
The first point I have to refer to is this: we have 
brought the sun and the stars together into line in all 
matters relating to the discussion of the effects of higher 
temperatures. The photographs taken during the recent 
solar eclipses show that when we deal with the hottest 
part of the sun that we can get at, which is hotter than 
that part of the sun which produces the well-known 
absorption spectrum marked by the so-called Fraunhofer 
lines, we are not in an unknown territory at all, but are 
brought face to face with similar phenomena to those in 
the atmospheres of stars which are hotter than our sun. 
The bright-line spectrum of the sun’s chromosphere 
seen during an eclipse shows us the effects produced by 
heat in the hottest part of the sun that we can reach ; 
these we can compare with the dark lines of a star 
which contains absorption lines very different from those 
represented by the Fraunhofer lines, and we find that 
they correspond almost line for line. 
In this manner then we have an opportunity of 
correlating all the facts which have been obtained 
during the last, let us say, thirty years, in relation to the 
sun, with more recent facts than have been gathered 
with regard to the stars. In this work we were, by 
hypothesis, watching the effects of dissociation as the 
temperature rose higher and higher; but if we change 
our point of view, if we consider the phenomena no | 
longer from the point of view of dissociation but from | 
that of evolution, we find at once that the facts recently | 
garnered carry us very far indeed along a new line of | 
thought. 
Let me give you an idea of what I mean. Let us deal, 
for instance, with well-known chemical compounds, say 
chloride of sodium, that is common salt, and oxide of 
iron, that is iron-rust. We have no difficulty in recog- 
nising the fact that chlorine and sodium in one case and 
oxygen and iron in the other must have existed before 
1A Lecture to Working Men, delivered at the Museum of Practical 
Geology on Monday, April 24, by Sir Norman Lockyer, K.C.B. 
NO. 1544, VOL. 60] 
| 
their compounds, common salt and iron rust, could be 
formed or associated. Water is split into hydrogen and 
oxygen at a high temperature, so that there is a temper- 
ature above which the two gases would remain in 
contact but uncombined ; when the temperature falls 
water is produced. Dissociation, therefore, in all its 
stages must reveal to us the forms the coming together 
of which has produced the thing dissociated or broken 
up by heat. If this be so, the final products of dissocia- 
tion or breaking up by heat must be the earliest chemical 
forms. Hence we must regard the chemical substances 
which visibly exist alone in the hottest stars as represent- 
ing the earliest evolutionary forms. That, I think, is 
pretty obvious. 
If we were only dealing with ordinary chemical forms 
it might be objected that it was only a question of seezag ; 
that all chemical substances were really present in the 
reversing layer, that is the part of the atmosphere of the 
stars which we can study, but some only made their ap- 
pearance ; but I shall show later that the orderly pro- 
gression includes lines of substances which we cannot 
see at all and others which we can only see at the highest 
possible temperatures in our laboratories. 
Two or three times over I have used the words 
“evolution” and ‘evolutionary forms.” What do these 
words really mean ? ; 
Perhaps I can give an idea of this by referring to 
another line of work altogether in which the word is fre- 
quently used and thoroughly understood. It is important 
that I should do this for another reason, which you will 
gather later. That line of work has to do, not with 
inanimate forms, like the chemical elements and the 
stars, but with living things, with so-called organisms. 
Some of my audience to-night doubtless remember 
Huxley’s lectures here in 1860 On the Relations of Man 
to the Lower Animals, and most of you know that what 
we now recognise as one of the greatest triumphs of the 
century just ending was the determination of the truth 
of a so-called “organic evolution” in which we have, 
I suppose, the most profound revolution in modern 
thought which the world has seen. 
That evolution tells us that each kind of plant and 
animal was not specially created, but that successive 
changes of form were brought about by natural causes, 
and that the march of these forms was from the more 
simple to the more complex. Organic evolution, in fact, 
may be defined as the production of new organic forms 
from others more or less unlike themselves ; so that all 
the present plants and animals are the descendants, 
through a long series of modifications or transform- 
ations, or both, of a limited number of an ancient simpler 
type. We must not suppose that this change has gone 
on as if things were simply mounting a ladder; the 
truth seems to be that we have to deal with a sort of tree 
with a common root and two main trunks representing 
animal and vegetable life ; each of these is divided into 
a few main branches, these into a multitude of branchlets, 
and these into smaller groups of twigs. : 
This new view represents to us the evolution of the sum 
of living beings; shows that all kinds of animals and 
plants have come into existence by the growth and modi- 
fication of primordial germs. Now I want just to say 
that this is no new idea, it is the demonstration which 
is new to us in our present century and generation ; we 
have really to go back to the seventeenth century, if 
indeed we must not go as far back as Aristotle, for the 
first germs of it; but with regard to the history, however, 
I have no time to deal with it. There are two or three 
points, however, to be considered in regard to this evolu- 
tion. The individual organic forms need not continuously 
advance ; all that is required is that there shall be a 
general advance—an advance like that of our modern 
civilisation—while some individual tribes or nations, as 
we know, stand still, or become even degenerate. With 
