THE CAUSES OF THE STRUGGLE. 311 



succeeds in gaining a step in the way of defence, 

 the other as quickly becomes more aggressive. 

 The more difficulties encountered by the species 

 the more experience it acquires, and therefore the 

 greatest developments take place in those which 

 have already overcome many obstacles. When a 

 plant or animal has settled down as it were, and 

 is no longer subject to the attacks of enemies or 

 the vicissitudes of the weather, it begins to re- 

 trograde, as we have seen in the case of our 

 cultivated flowers. It frequently happens, however, 

 that this degradation is prevented by efforts in 

 other directions the plants do not require such 

 hard, wiry stems and hairy leaves as when growing 

 outside the garden, and therefore devote their 

 energies to extraordinary developments in their 

 flowers. Such cases, although from one point of 

 view appearing to be weak and degenerate, are 

 really examples of hard work and accommodation 

 to new circumstances. 



The theory of continuous existence seems to be 

 very useful in explaining some of the problems 

 of human life. Loti, in his " Book of Pity and 

 Death," says : " The human head is filled with 

 innumerable memories, heaped up pell-mell like 

 the threads in a tangled skein. There are thou- 

 sands and thousands of them hidden in obscure 



