CREATION AND EVOLUTION. 319 
can be proved, in any case, is that no known: natural 
cause is competent to produce a given effect; and it is 
an obvious blunder to confound the demonstration of our 
own ignorance with a proof of the impotence of natural 
causes. However, apart from the philosophical worth- 
lessness of the hypothesis of creation, it would be a waste 
of time to discuss a view which no one upholds. And, 
unless I am greatly mistaken, at the present day, no 
one possessed of knowledge sufficient to give his opinion 
importance is prepared to maintain that the ancestors of 
the various species of crayfish were fabricated out of in- 
organic matter, or brought from nothingness into being, 
by a creative fiat. 
Our only refuge, therefore, appears to be the hypo- 
thesis of evolution. And, with respect to the doctrine 
of abiogenesis, we may also, in view of a proper 
economy of labour, postpone its discussion until such 
time as the smallest fragment of evidence that a crayfish 
can be evolved by natural agencies from not living matter, 
is brought forward. 
In the meanwhile, the hypothesis of transformism 
remains in possession of the field; and the only pro- 
fitable inquiry is, how far are the facts susceptible of 
interpretation, on the hypothesis that all the existing 
kinds of crayfish are the product of the metamorphosis 
of other forms of living beings; and that the bio- 
logical phenomena which they exhibit are the results 
of the interaction, through past time, of two series of 
