THE INSURGENCE OF LIFE 141 



molluscs, and sea-urchins the crowns being smooth and 

 rounded ; and in the care for the pup which the mother 

 shows, dandling it, and diving with it. 



The Penelope Spider. Not only do living creatures 

 fill every cranny in the rock-pool, every nook in the 

 grassy bank, they take advantage of every niche of 

 opportunity. The illustrations are world- wide. Professor 

 Goeldi gives us one from a garden near Para. The time is 

 long before dawn and the chief actor is a spider, spinning 

 in the dim light. Before the sun rises her web is finished, 

 and it serves to catch the winged male scale-insects in 

 their early morning nutter. But as the sun rises, the 

 spinner grows restless ; she dislikes the light of day, just 

 as does the poacher who has by night spread in the field 

 his net for birds. So, at the dawning, the spider draws 

 her net together with its quivering delicate captives, and 

 retires into the shade to investigate the catch. It was only 

 by staying up all night in the garden that Professor Goeldi's 

 son discovered the secret of this light-avoiding spider whose 

 web disappears with the morning dew. It is a mode of 

 bread-winning that fills a curious niche of opportunity. 

 Penelope-like, the spinner makes and unmakes her web 

 each day, but not without effective results to man (by 

 destroying the injurious scale- insects) as well as to herself. 



Successive Waves of Life. The pressing insurgence 

 of life which is illustrated by the way in which organisms 

 fill every niche even the least inviting is illustrated in 

 quite another way when we observe a sequence of possessors 

 passing like waves over a particular environment. When 

 one horde has made an area uninhabitable for itself by 

 exhausting the food-supply, there may come another able 

 to cut even closer to the bone. We see this in a very 



