20* The Outline of Science 



animal a new opportunity to test variations in structure which 

 arise mysteriously from within, as expressions of germinal 

 changefulness rather than as imprints from without. For of the 

 transmissibility of the latter there is little secure evidence. 



Experiments in Locomotion 



It is very interesting to think of the numerous types of 

 locomotion which animals have discovered pulling and punting, 

 sculling and rowing, and of the changes that are rung on these 

 four main methods. How striking is the case of the frilled lizard 

 (Chlamydosaurus) of Australia, which at the present time is, as 

 it were, experimenting in bipedal progression always a rather 

 eventful thing to do. It gets up on its hind-legs and runs totter- 

 ingly for a few feet, just like a baby learning to walk. 



How beautiful is the adventure which has led our dipper or 

 water-ouzel a bird allied to the wrens to try walking and fly- 

 ing under water ! How admirable is the volplaning of numerous 

 parachutists "flying fish," "flying frog," "flying dragon," 

 "flying phalanger," "flying squirrel," and more besides, which 

 take great leaps through the air. For are these not the splendid 

 failures that might have succeeded in starting new modes of flight? 



Most daring of all, perhaps, are the aerial journeys under- 

 taken by many small spiders. On a breezy morning, especially 

 in the autumn, they mount on gateposts and palings and herbage, 

 and, standing with their head to the wind, pay out three or four 

 long threads of silk. When the wind tugs at these threads, the 

 spinners let go, and are borne, usually back downwards, on the 

 wings of the wind from one parish to another. It is said that 

 if the wind falls they can unfurl more sail, or furl if it rises. In 

 any case, these wingless creatures make aerial journeys. When 

 tens of thousands of the used threads sink to earth, there is a 

 "shower of gossamer." On his Beagle voyage Darwin observed 

 that vast numbers of small gossamer spiders were borne on to the 

 ship when it was sixty miles distant from the land. 



