Diverse Adaptations 69 



ticularly adapted to life in a very unpromising inland 

 environment, while the other has, so to speak, gone to 

 sea.- Thus have animals blazed the trails which man 

 has followed. Another point of evolutionary interest 

 is that, while there are many different species of giant 

 tortoise on the different Galapagos Islands, illus- 

 trating the influence of isolation in evolution, there is 

 only one kind of sea-lizard, for it differs from the 

 tortoises in being able to swim from island to island, 

 and is thus untethered in its inter-crossing. Who can 

 wonder that Darwin was prompted to evolutionist 

 thinking by his visit to the "Enchanted Islands," as 

 they used to be called? 



§7. Anatomical Arguments. 



The anatomist has also made his contributions to 

 the "evidences," showing how the same fundamental 

 material — say, that used in the making of fore-limbs 

 — is moulded and shaped into diverse forms. As Dar- 

 win said: "How inexplicable is the similar pattern 

 of the hand of a man, the foot of a dog, the wing of 

 a bat, the flipper of a seal, on the doctrine of inde- 

 pendent acts of creation! How simply explained on 

 the principle of the natural selection of successive 

 slight variations in the diverging descendants from 

 a single progenitor !" 



Structures that resemble one another in funda- 

 mental structure and in the way in which they develop 

 are said to be homologous, and the tracing out of 

 homologies speaks of evolution at every turn. A bird's 

 wing is at first sight conspicuously different from the 



