324 SCIENCE PROGRESS 



ever receiving fresh illustration ; but on the immaterial, that small causes, 

 acting cumulatively over long periods of time, produce effects of immeasurable 

 greatness, is a doctrine that received striking extensions of application in the 

 last century, especially at the hands of Darwin and Lyell. 



Thirdly, an obvious corollary of the other two, the uninterrupted process 

 of things in a smooth unbroken course, sliding from one state of things into 

 the next, and making neither stop nor jump, " Natura non facit saltum" is 

 a saying not only old, but also true. 



With these principles Darwinism is thoroughly in harmony. It was an 

 advance of the mind of man upon already familiar lines. Putting it roughly 

 and roundly, Darwin and Wallace asserted that time may change an amoeba 

 into a monkey and a monkey into a man by the age-long accumulation of 

 small differences, such as may to-day be seen between two plants or two 

 animals of the same species, whether wild or in domestication. 



An equal consonance with these old-established truths may be claimed 

 for Precession. Take the small amount of Precocity that may any day be 

 seen occurring in a single generation, multiply it by the number of generations 

 supposed to have intervened between now and (say) the Eocene, and the 

 resulting changes might perhaps be as marvellous as those which have 

 happened. Not only so, but Precession is even a necessary supplement to 

 Darwinism, showing as it does how that constant accumulation of small 

 increases of size or development or both, which Darwin postulated as occurring 

 through thousands of generations, every one of them involving a small increase 

 in the time consumed in the growth of the individual, is made possible without 

 an inordinate increase in the total length of the growth-time, and the post- 

 ponement to a hazardous future of the attainment of maturity. Were it 

 not for the slow but unceasing compression in point of time of all its develop- 

 ments except the last, and of that last as soon as in the next generation it 

 has become penultimate, no animal of the higher orders of now-existing life 

 could have ever come into being at all. All their progenitors must have 

 perished on the long journey to maturity. 



Mutation, on the other hand, is the child of a reaction against Darwinism, 

 and in direct opposition to the three ancient principles I have cited, denies 

 the sufi&ciency of an accumulation of small changes to produce such vast 

 results. It thus traverses the belief that Nature is in a state of constant 

 change and flux, for the sudden jumps by which species are supposed 

 to have arisen must have alternated with periods of rest, or what has 

 become of the effects of the series of small changes which intervened ? 

 Moreover, Mutation to my thinking is an explanation which does not 

 explain ; it is nothing but special creation by more or less numerous 

 instalments. 



In the kindred science of Geology there is an instructive parallel and 

 precedent for such a departure as this from the long accumulation of human 

 experience gathered and enshrined in the three doctrines cited. At the 

 beginning of the nineteenth century there were two competing views as to 

 the origin of those surface-rocks that come within our purview, called by 

 Whewell the Catastrophic and the Uniformitarian. The following account 

 of the former is taken from Prof. J. W. Judd's Cambridge Manual, " The 

 Coming of Evolution " : " That at a number of successive epochs — of which 

 the age of Noah was the latest — great revolutions had taken place on the 

 earth's surface ; that during each of these cataclysms all living things were 

 destroyed ; and that, after an interval, the world was restocked with fresh 

 assemblages of plants and animals to be destroyed in turn and embedded in 

 the strata at the next revolution." In other words, that the course of 

 Nature in the building of the world in times long past had been discon- 

 tinuous, by jumps or Geological Mutations. Our present Mutationists are 

 the Catastrophists of Biology ; ' ' discontinuity ' ' is ever on their lips , Lamarck, 



