16 EVOLUTION AND THE 
to involve an arbitrary infringement of the Uniformity 
of Nature? 
They would both have us believe that living matter 
came into being by the operation of natural causes— 
that is, by the unhindered play of natural affinities 
operating in and upon matter which had already 
acquired a certain degree of molecular complexity. 
They believe that the simpler kinds of mineral and 
crystalline matter continue to come into being now 
as they have ever done; nay, more, they believe 
that the higher kind of matter, originally initiated 
by the operation of natural causes, continues to ‘grow’ 
both in animal and in vegetal forms, solely under 
similar influences, and yet they consider themselves 
justified in supposing that natural causes are now 
no longer able independently to initiate this living 
matter or protoplasm. Again, we find Professor 
Tyndall* also affirming, in the most unhesitating 
language, the ultimate similarity between crystalline 
and living matter: affirming that all the various 
_ structures by which the two kinds of matter may be 
represented are equally the “ results of the free play 
i of the forces of the atoms and molecules” entering 
into their composition. And yet he, too, would have 
us believe that whilst differences in degree of mole- 
cular complexity alone separate living from not-living 
* Fragments of Science, qth edit. (1872), pp. 85—87, and 113—119. 
