348 



CHAPTERS ON EVOLUTION. 



existence of the tendency to the production of variations, then, 

 whether the variations which are produced shall survive and supplant 

 the parent, or whether the parent form shall survive and supplant the 

 variations, is a matter which depends entirely on those conditions 

 which give rise to the struggle for existence. If the surrounding 

 conditions are such that the parent form is more competent to deal 

 with them and flourish in them than the derived forms, then in the 

 struggle for existence the parent form will maintain itself, and the 

 derived forms will be exterminated. But if, on the contrary, the 

 conditions are such as to be more favourable to a derived than to the 

 parent form, the parent form will be extirpated, and the derived form 

 will take its place. In the first case, there will be no progression, no 

 change of structure, through any imaginable series of ages ; in the 

 second place, there will be modification and change of form." To 

 the same end Darwin himself leads us. In one or two very pregnant 



passages, the author of the 

 "Theory of Natural Selection" 

 very plainly indicates why pro- 

 gression should not be universal, 

 and why certain beings remain 

 lowly organised whilst others 

 attain to the summit and pin- 

 nacle of their respective organi- 

 sations. " How is it," says 

 Darwin, " that throughout the 

 world a multitude of the lowest 

 forms still exist? and how is it 



that in each great class some 

 forms are far more highly de- 

 veloped than others ? Why have 

 not the more highly developed 

 forms everywhere supplanted 

 and exterminated the lower?" 

 Answering his own queries, 

 Darwin says that natural selec- 

 tion by no means includes " pro- 

 gressive development it only 

 takes advantage," he remarks, 

 " of such variations as arise and 

 are beneficial to each creature 



under its complex relations of life. And it may be asked, what 

 advantage, as far as we can see, would it be to an infusorian 

 animalcule to an intestinal worm or even to an earthworm, to be 

 highly organised? If it were no advantage, these forms would be 

 left, by natural selection, unimproved or but little improved, and 



FIG. 248. GLOBIGERINA, ETC. 



