STRUOQLE FOR EXISTENCE, GO 



Hence it is quite credible that the presence of a feline 

 animal in large numbers in a district might determine, 

 through the intervention first of mice and then of bees, 

 the frequency of certain flowers in that district! 



In the case of every species, many different checks, act- 

 ing at different periods of life, and during different seasons 

 or years, probably come into play; some one check or some 

 few being generally the most potent; but all will concur in 

 determining the average number, or even the existence of 

 the species. In some cases it can be shown that widely 

 different checks act on the same species in different dis- 

 tricts. When we look at the plants and busbes clothing 

 an entangled bank, we are tempted to attribute their pro- 

 portional numbers and kinds to what we call chance. But 

 how false a view is this! Every one has heard that when 

 an American forest is cut down, a very different vegetation 

 springs up; but it has been observed that ancient Indian 

 ruins in the Southern United States, which must formerly 

 have been cleared of trees, now display the same beautiful 

 diversity and proportion of kinds as in the surrounding 

 virgin forests. What a struggle must have gone on during 

 long centuries between the several kinds of trees, each 

 annually scattering its seeds by the thousand; what war 

 between insect and insect — between insects, snails and 

 other animals with birds and beasts of prey — all striving to 

 increase, all feeding on each other, or on the trees, their 

 seeds and seedlings, or on the other plants which first 

 clothed the ground and thus checked the growth of the 

 trees! Throw up a handful of feathers and all fall to the 

 ground according to definite laws; but how simple is the 

 problem where each shall fall compared to that of tlie 

 action and reaction of the innumerable plants and animals 

 which have determined, in the course of centuries, the 

 proportional numbers and kinds of trees now growing on 

 the old Indian ruins! 



The dependency of one organic being on another, as of a 

 parasite on its prey, lies generally between beings remote 

 in the scale of nature. This is likewise sometimes the 

 case with those which may be strictly said to struggle with 

 each other for existence, as in the case of locusts and grass- 

 feeding quadrupeds. But the struggle will almost invari- 

 ably be most severe between the individuals of the same 



