METEORITES, AND THE ORIGIN OF LIFE. 
393 
of the electric light when the arc is surrounded by a gaseous 
hydrocarbon. Carbon is the characteristic element of the 
organic compounds of which all things living are built up. 
“ Who can say,” he asks, “ whether these bodies which wander 
about through space may not also strew germs of life where a 
new heavenly body has become fitted to offer a habitat to 
organized creatures ? ” The hypothesis, in the form set forth in 
1871 by Professor Helmholtz and Sir William Thomson, was 
vigorously handled by Zollner, of Leipzig, whose work, “ Ueber 
die Natur der Cometen,” appeared in the following year. In 
the Vorrecle of his book he passes his countryman by unmen- 
tioned, but declares Sir William Thomson’s proposition to be 
unscientific, and that in a twofold sense. In the first place, he 
maintains it is unscientific in a formal or logical sense, in that 
it changes the original simple question, Why has our earth 
become covered with organisms ? into a second, Why had that 
heavenly body the fragment of which fell upon our planet 
become covered with vegetation, and not our earth itself ? “ If, 
however,” he adds, “bearing in mind an earlier dictum,* we regard 
inorganic and organic matter as two substances from all eternity 
diverse, just as in accordance with our present views we con- 
sider two chemical elements to be diverse, such an hypothesis 
as that now advanced must be at variance with the destructi- 
bility of organisms by heat which experience has taught us.” 
“Again,” contends Zollner, “the hypothesis in its material 
bearing is unscientific. When a meteorite plunges with pla- 
netary velocity into our atmosphere, the loss of vis viva arising 
from friction is converted into heat, which raises the tempera- 
ture of the stone to a point where incandescence and combus- 
tion take place. This, at all events, is the theory at present 
generally held to explain the phenomena of star-showers and 
fire-balls. A meteorite, then, laden with organisms, even if it 
could withstand the sundering of the parent mass unscathed, 
and should take no part in the general rise of temperature 
resulting from this disruption, must of necessity traverse the 
earth’s atmosphere before it could deliver at the earth’s surface 
organisms to stock our planet with living forms.” f 
Helmholtz did not long delay in replying to Zollner’s criti- 
cism on this question. An opportunity occurred during the 
publication, in the following year, 1873, of the second part of 
the Gferman translation of Thomson and Tait’s “ Handbook of 
Theoretical Physics.” The preface contains Helmholtz’s 
* “Dead matter cannot become living matter unless it be subject to the 
influence of matter already living.” 
t “Ueber die Natur der Cometen. Yon J. C. P. Zollner.” Leipzig: 
Engelmann. 1872. p. 24. 
NEW SERIES, VOL. I. — NO. IV. 
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