12 NO STRUGGLE NO SELECTION 



and 1900 which have perished because their variations 

 were inferior. But how did they perish ? They did 

 not pass out of existence like a dream of the night, 

 nor without material means being employed. Let us 

 then ask how they perished. It is well known to 

 those familiar with their haunts that tigers do not 

 attack or kill one another, except on the rare 

 occasions when two, equally matched, fight over a 

 kill which one of them has made. Accordingly, if I 

 strike off from the amount 50 tigers killed in inter- 

 necine strife, you must admit that I have made you 

 a generous gift ; for I do not imagine that the number 

 that perish in this manner amount to a tithe of what 

 I have said. There still remain 1850 tigers to be 

 eliminated in the course of a generation before any of 

 them survive to procreate its kind. They do not 

 destroy each other, and they have no other enemies 

 that can destroy them ; for when the young are old 

 enough to come forth from their dens, their parents 

 protect them too effectually to permit of any other 

 carnivorous beast attacking them. How, then, does 

 their elimination take place ? " 



To this my friend replied : " Their elimination must 

 be constantly taking place, so that it is improbable there 

 would be alive at any one time as many as 1000 young 

 tigers in all. Darwin says the causes which check the 

 natural tendency of each species to increase are most 

 obscure. He resolves the question of surviving or 

 perishing into a matter of the food supply: and I 

 should imagine that in an area which has been fully 



