102 Correlation of Organisms 



many other circles. The face of Nature is like the 

 surface of quiet water on a summer evening when the 

 touches of the May-Flies dimple it into a multitude 

 of interacting circles. Or it is like the lea quivering 

 with threads of fallen gossamer. To put it in the 

 coldest way, there seems to be a tendency in Animate 

 Nature towards the correlation of organisms. This 

 is one of the central ideas of Darwinism, and if we 

 ask how this stands to-day, the answer must be, 

 "Clearer than ever." Every year brings fresh in- 

 stances of the Web of Life. Nature is seen more and 

 more vividly as a fabric. Let us take a number of vivid 

 instances. 



One of the plants most inimical to man's interests 

 is the bracken, for it destroys good pasture and it 

 is so sturdy and insurgent that it can conquer even 

 the heather. The encroachments may be met by la- 

 borious cutting and by spraying with sulphuric acid, 

 but it would be more promising to discover new uses 

 for the fern. It makes excellent bedding, it has strong 

 antiseptic qualities, it contains a considerable quan- 

 tity of potash, and so on. A few experiments have 

 shown that the fish-yield of fresh-water lochs can be 

 greatly improved by pitching cartloads of cut 

 bracken into the waters. Their slow decay promotes 

 the multiplication of animalcules, on which small 

 crustaceans and the like depend, and thus the fishes 

 are fed. These experiments should be continued, for 

 it may be that bracken cast upon the waters will 

 return to us after many days in the form of trout. 



Everyone knows that widely separated forms of 



