22 EVOLUTION AND THE 
periods of vibration, is emitted from the sun and 
from the fixed stars. . . . We are thus assured 
that molecules of the same nature as those of our 
hydrogen exist in those distant regions, or at least 
did exist when the light by which we see them was 
emitted.” With evidence such as this before us, 
which could be multiplied to an enormous extent, 
we should hesitate before needlessly postulating 
any infringement of the uniformity of natural 
phenomena: we ought in fact only to entertain 
such a supposition when it has been lightly forced 
upon us. Certainly we should not resort to it 
and then strain the interpretation of natural and 
experimental phenomena into a forced accord- 
ance. 
What, then, are the reasons assigned for. the non- 
occurrence at the present day of the process of 
Archebiosis? All that Mr. Spencer says upon the 
subject is, that such a process seems to him more 
likely to have occurred at “a time when the heat 
of the earth’s surface was falling through those ranges 
of temperature at which the higher organic com- 
pounds are unstable,” than at the present day. Why 
such conditions would be more favourable than 
those now existing Mr. Spencer does not say; and 
that such an alteration should suffice to put a stop 
to Archebiosis, although we see living matter still 
