PREFACE. xiii 



which has existed for millions and millions of years 

 without having undergone any differentiation ? Would 

 he have us believe that the simplest and most struc- 

 tureless Amoeba of the present day can boast of a line 

 of ancestors stretching back to such far-remote periods 

 that in comparison with them the primaeval men were 

 but as things of yesterday? The notion surely is 

 preposterously absurd ; or, if true, the fact would be 

 sufficient to overthrow the very first principles of their 

 own Evolution philosophy. Again, may we not see at 

 the present day all those minute shades of difference 

 by which the primordial fissiparous act of reproduction 

 gives place to the more and more specialized forms 

 of bisexual reproduction? Even this could scarcely 

 occur unless the excessively changeable forms of life 

 which supply us with these various transitions were 

 continually seething into existence afresh. Instead of 

 having to do with a pretty accurate picture of the 

 original process of evolution, each sectional mosaic of 

 which has been faithfully transmitted for millions of 

 years with little or no variation, we probably stand face 

 to face with processes that have been independently 

 repeated billions and billions of times and repeated 

 in a more or less similar manner, simply because the 

 processes themselves have always been the results of 

 the conjoint action of the same external forces in 

 conflict with similar material properties or tendencies. 

 Like causes should produce like results: so that the 

 primordial living units of to-day should undergo changes 

 which are, in the main, similar to those passed through 

 by the units of living matter which first came into 

 being upon the surface of our globe. 



