STRUGGLE FOR EXISTENCE 85 



from a few wheat or other such plants in a garden : I have 

 in this case lost every single seed. This view of the neces- 

 sity of a large stock of the same species for its preservation, 

 explains, I believe, some singular facts in nature such as that 

 of very rare plants being sometimes extremely abundant, in 

 the few spots where they do exist; and that of some social 

 plants being social, that is abounding in individuals, even on 

 the extreme verge of their range. For in such cases, we 

 may believe, that a plant could exist only where the condi- 

 tions of its life were so favourable that many could exist 

 together, and thus save the species from utter destruction. 

 I should add that the good effects of intercrossing, and the 

 ill effects of close interbreeding, no doubt come into play 

 in many of these cases; but I will not here enlarge on this 

 subject. 



COMPLEX RELATIONS OF ALL ANIMALS AND PLANTS 



TO EACH OTHER IN THE STRUGGLE 



FOR EXISTENCE 



Many cases are on record showing how complex and un- 

 expected are the checks and relations between organic 

 beings, which have to struggle together in the same coun- 

 try. I will give only a single instance, which, though a 

 simple one, interested me. In Staffordshire, on the estate 

 of a relation, where I had ample means of investigation, 

 there was a large and extremely barren heath, which had 

 never been touched by the hand of man ; but several acres 

 of exactly the same nature had been enclosed twenty-five 

 years previously and planted with Scotch fir. The change 

 in the native vegetation of the planted part of the heath 

 was most remarkable, more than is generally seen in pass- 

 ing from one quite different soil to another: not only the 

 proportional numbers of the heath-plants were wholly 

 changed, but twelve species of plants (not counting grasses 

 and carices) flourished in the plantations, which could not 

 be found on the heath. The effect on the insects must have 

 been still greater, for six insectivorous birds were very com- 

 mon in the plantations, which were not to be seen on the 

 heath; and the heath was frequented by two or three dis- 

 tinct insectivorous birds. Here we see how potent has been 



