THE STRUGGLE FOR EXISTENCE. 



143 



mice, which destroy their combs and nests; and Colonel 

 Newman, who has long attended to the habits of humble- 

 bees, believes that more than two-thirds of them are thus 

 destroyed all over England. Now, the number of mice 

 is largely dependent, as every one knows, on the number 

 of cats; and Colonel Newman says, ' Near villages and 

 small towns I have found the nests of humble-bees more 

 numerous than elsewhere, which I attribute to the num- 

 ber of cats that destroy the mice. Hence it is quite 

 credible that the presence of a feline animal in large num- 

 bers in a district might determine, through the interven- 

 tion first of mice and then of bees, the frequency of cer- 

 tain flowers in that district.' " 



The closer the kindred of the competitors, the more 

 ardent is the struggle for the existence; for the more 

 adjacent organisms differ in their requirements, the less 

 do they interfere with one another, and the more will 

 each be able to exhaust the resources of the vicinity for 

 its own benefit. This seems to be flatly contradicted by 

 the great series of associated plants and animals; but 

 on closer inspection they also form no exception to the 

 rule, as, often by their very number they render existence 

 possible and easy to one another, and increase exactly 

 in the degree permitted by the stock of nutriment. If 

 Among associated plants or gregarious animals a surplus 

 firoduction occurs, competition and conflict instantly 

 Commence, and life is regulated in every respect ex- 

 actly as in species less remarkable for the number of indi- 

 viduals. 



Our proposition that the vehemence of the struggle 

 rises with the closeness of the kindred, is thus univer- 

 sally valid. Such a rapid war of extermination is rarely 



