162 THE MEANING OF EVOLUTION 
entirely sure that life is not amenable to physics or 
chemistry that we can hardly conceive of the possi- 
bility of its originating out of matter in the test tube. 
If it does so come, and when it does so come, this 
will not prove that life is a less noble and less wonder- 
ful thing than we thought. It will only prove that 
chemistry and physics are more noble and more won- 
derful than we dreamed. 
There is another way of approaching this life prob- 
lem, though it seems to be rather a begging of the 
question than a solution of it. Of recent years it has 
been discovered that even the very low temperatures 
obtained by evaporating liquid air, say three hundred 
degrees below zero, Fahrenheit, do not kill seeds or 
spores of mold. The space between the planets is un- 
doubtedly extremely cold. We have always supposed 
it to be entirely too cold for life to exist in it. But 
we laid little stress on the fact because we had no 
thought of any possible life existing there. But the 
discovery that seeds and spores can live uninjured 
through extreme cold has led to an interesting sug- 
gestion. This is that when the earth became adapted 
to the presence of life it was infected by germs trans- 
ported on meteors from some other system. Accord- 
ing to this theory, organic dust through space is ready 
to infect any planet which offers the conditions under 
which life may arise. Of course this theory does not 
