DARWINISM AND EVOLUTION DEFINED. 15 



for existence due to the fortuitous possession of fortunate 

 congenital differences (variations). The nine hundred and 

 ninety with unfortunate congenital variations are extin- 

 guished in the struggle and with them the opportunity 

 for the perpetuation (by transmission to the offspring) of 

 their particular variations. There are thus left ten to re- 

 produce their advantageous variations. The offspring of 

 the ten of course will vary in their turn, but will vary around 

 the new and already proved advantageous parental condi- 

 tion : among the thousand, say, offspring of the original 

 saved ten the same limitations of space and food will again 

 work to the killing off before maturity of nine hundred and 

 ninety, leaving the ten best equipped to reproduce. This 

 repeated and intensive selection leads to a slow but steady 

 and certain modification through the successive generations 

 of the form and functions of the species; a modification 

 always towards adaptation, towards fitness, towards a 

 moulding of the body and its behaviour to safe conformity 

 with external conditions. The exquisite adaptation of the 

 parts and functions of the animal and plant as we see it 

 every day to our infinite admiration and wonder has all 

 come to exist through the purely mechanical, inevitable 

 weeding out and selecting by Nature (by the environmental 

 determining of what may and what may not live) through 

 uncounted generations in unreckonable time. This is Dar- 

 win's causo-mechanical theory to explain the transformation 

 of species and the infinite variety of adaptive modification. 

 A rigorous automatic Natural Selection is the essential idea 

 in Darwinism, at least in Darwinism as it is held by the 

 present-day followers of Darwin. 



What auxiliary and supporting factors Darwin considered 

 possibly or certainly of some influence or effect in species- 

 Artificial forming we may postpone reference to until 

 selection, our more particular examination of the natural 



selection theory in succeeding chapters of this book. Simi- 



