42 ANIMAL LIFE AND HUMAN PROGRESS 



their turn to reproduce their kind. This, however, would 

 deprive the term of nearly all meaning in relation to Natural 

 Selection, for on an average of years the numbers of such 

 individuals remain constant in any given species. 



I think that we may take it that fecundity is an adaptation 

 preserved by Natural Selection, rather than that adaptations 

 are a consequence of fecundity through the operation of 

 Natural Selection. 



Now let us turn to the phenomena of variability and inherit- 

 ance, so closely bound up with adaptation, and, as Darwin 

 said, " almost implied by reproduction." 



Inheritance and variation are familiar facts, the one term 

 expressing our experience that offspring resemble their parents, 

 the other that, inheritance notwithstanding, the offspring 

 never exactly resemble their parents. 



Denning Natural Selection as the process whereby indi- 

 viduals which display variations giving them ever so small a 

 superiority over their fellows have the best chance of survival, 

 while less happily endowed individuals succumb in the struggle 

 for existence, the theory of Darwin and Wallace asserts that 

 Natural Selection, seizing upon favourable variations, as a 

 breeder selects desirable deviations of structure in his cattle, 

 fixes them by inheritance, and, by a continuance of this 

 process through many generations, is able to accumulate slight 

 variations in a given direction until the most complex organs 

 are produced. 



From which arises the corollary that if there is no com- 

 petition there is no struggle for existence, and if there be no 

 struggle there is no selection of favourable variations, and the 

 race cannot improve. 



It is assumed by the adherents of the theory, and Wallace 

 laid special stress on the point, that variations can be accumu- 

 lated by selection, to almost any desired degree, in a definite 

 direction. The assumption is a necessary part of the theory, 

 for if there is a limit to the amount of variation the power 

 attributed to selection could not exist. Darwin, however, 

 was much more cautious and always much more responsive 

 to sound criticism than Wallace. For reasons that will be 



