I3i6 LIFE : OUTLINES OF GENERAL BIOLOGY 



We thus need to look more fully into the facts of the case. Living 

 creatures are continually being confronted with all but overwhelming 

 difficulties and thwarting limitations. For some of these the living 

 creatures are themselves responsible; for they multiply so rapidly 

 that there is not enough of food to go round, or even not enough 

 room to grow up in. We must recognise too that in the course of 

 time "nutritive chains" have been established, one creature eating 

 another, and that another, through long series. Beyond that there 

 is the self-assertiveness of the vigorous creature. The lusty animal 

 tends to be at times a hustler, elbowing its way through the crowd, 

 though at another time it may almost surpass woman in its gentle- 

 ness. Not less important is the irregular changefulness and in- 

 hospitality of the physical environment. In the crowdedness, the 

 carnivorousness, and the unpredictable vicissitudes of the callous 

 surroundings we see three reasons for the struggle for existence, 

 and the fourth is to be found in the insargence of life. 



We have then an almost universal picture — insurgent creatures 

 with a will to live and, surrounding them, all manner of baffling 

 difficulties and thwarting limitations. Whenever the creature 

 "answers back", reacts, asserts itself, girds up its loins against 

 these difficulties, there is the struggle for existence. Where organisms 

 do nothing or can do nothing — like the myriads of "sea-butterflies" 

 engulfed in the huge cavern of a baleen whale's mouth — there 

 seems no utility in speaking of the struggle for existence. For the 

 central idea is that of "clash" between one organism and another 

 or between organisms and the inanimate forces of Nature. 



The struggle may be (i) between fellows of the same kith and kin, 

 as when locust turns upon locust, and female spider on male spider, 

 and stag upon stag, or as in the cannibalism in the cradle that 

 occurs in the egg-capsules of the whelk. Or it ma}/ be between nearly 

 related species, which Darwin illustrated by reference to the com- 

 petition of brown rat and black rat — a reference to be considered, 

 however, in the light of the facts submitted by Chalmers Mitchell 

 in his Evolution and the War (1915). The struggle may be (2) between 

 foes of entirely different nature, for instance between carnivores 

 and herbivores, between birds of prey and small mammals, between 

 heather and bracken on the hills, between different kinds of trees 

 in the tropical forest. The struggle may be (3) between living 

 creatures and the inanimate conditions of their life- for instance, 

 between mammals and the winter, between plants and drought, 

 between birds and the storm. Thus Darwin spoke of the struggle 

 of a plant on the edge of the desert. 



When we compare the struggle between fellows and the struggle 

 between foes with the third form of struggle, which we may describe 

 as between living creatures and "Fate", we see that in the third 

 mode the element of competition has dropped out. Thus perhaps 



