36 ay THE TENDENCY OF VARIETIES TO DEPART 



irruption of some new carnivorous animal seeking 

 " pastures new " any change in fact tending to 

 render existence more difficult to the species in 

 question, and tasking its utmost powers to avoid 

 complete extermination ; it is evident that, of all 

 the individuals composing the species, those forming 

 the least numerous and most feebly organized 

 variety would suffer first, and, were the pressure 

 severe, must soon become extinct. The same .causes 

 continuing in action, the parent species would next 

 suffer, would gradually diminish in numbers, and 

 with a recurrence of similar unfavourable conditions 

 might also become extinct. The superior variety 

 would then alone remain, and on a return to 

 favourable circumstances would rapidly increase in 

 numbers and occupy the place of the extinct species 

 and variety. 



Superior Varieties will ultimately Extirpate the original 

 Species. 



The variety would now have replaced the species, 

 of which it would be a more perfectly developed 

 and more highly organized form. It would be in 

 all respects better adapted to secure its safety, and 

 to prolong its individual existence and that of the 

 race. Such a variety could not return to the ori- 

 ginal form ; for that form is an inferior one, and 

 could never compete with it for existence. Granted, 

 therefore, a u tendency " to reproduce the original 

 type of the species, still the variety must ever re- 



