THE DRAMA OF LIFE 27 



cesses which have their seat in the higher centres of the 

 brain may come to the aid of the inborn instinctive pro- 

 cesses which are localized in lower centres. And apart 

 altogether from intelligence and instinct there are many 

 striking cases of what may be metaphorically called suc- 

 cessful inventions or ' shifts for a living ', which depend on 

 structural peculiarities of the organism gradually perfected 

 through the ages. Without seeking to analyse at this 

 stage, we wish to notice some of these life-saving and life 

 furthering adaptations of structure and behaviour, which 

 it is one of the charms of Natural History to discover. Just 

 as in the human drama we see disguise and mask, imitation 

 and bluff, underhand devices and clever escapes, so it is 

 in the animal world, though the psychology of the matter 

 is in most cases entirely different. 



Over and over again in the history of animal life the 

 situation has been saved by some thorough change (which 

 doubtless took time to effect) in habitat or habit. The 

 earthworms, springing probably from an aquatic stock, 

 discovered the subterranean world, and must have enjoyed 

 a prolonged golden age beneath the ground, until centipedes, 

 burrowing beetles, and eventually moles came to trouble 

 them in their deep retreats. A temporary prosperity must 

 have likewise rewarded the invasion of the air by insects, 

 until flying reptiles, birds, and bats discovered the secret 

 as well ; or the adoption of a marine habit by the ancestors 

 of our modern Cetaceans, Pinnipeds, sea-turtles, and sea- 

 snakes. What success must have rewarded the birds' 

 discovery of migration, or the hibernating mammals' very 

 different device of evading the hardships of winter ! In 

 hundreds of different ways, at point after point, life has 

 saved the situation by a change of tactics. 



