360 THE EVOLUTION THEORY 



we can prove that many have ah-eady succumbed in the strugtrle 

 with man, and we anticipate the extermination of others. But the 

 reason why the}' are so readil}' exterminated obviousl}^ lies in the fact 

 that they have surrendered the advantage given to them by their bird- 

 nature, by adapting themselves to terrestrial life, and that they are 

 not able to regain it, at least not in the short time that is at their 

 disposal if they are to be saved from extermination. The best 

 example of this is the Dodo (fJkhis irieptui<). This remarkable-look- 

 ing bird, of about the size of a SAvan, lived in flocks upon the island of 

 Mauritius until about the end of the seventeenth century-. It had 

 small Avings with short quills which were useless for flight. As it 

 could neither escape by flight nor through the water, and could only 

 move clumsil}' and awkwardly' upon land with its short legs and 

 heavy body, it was hopelessly doomed as soon as a stronger enemy 

 made his appearance. It fell a victim to the sailors who first landed 

 on the island and clubbed it with sticks in huoe numbers. Until that 

 event it was without doubt excellentl}' adapted to life on that fertile 

 island, for on a volcanic island in the middle of the ocean there were 

 no large enemies, and it was therefore not dependent on the power of 

 flight for safety, and could pick up almndant^ food from the ground. 

 But when man suddenly appeared on the scene and began to per- 

 secute it, it was not the ' senile rigidity ' of its organization that 

 j^revented it from making use of its wings again ; it Avas the slowness 

 of variation and consequently of selection, whicli is common to all 

 species, AAdiich impelled it to extinction. The same fate Avill probably 

 OA^ertake the KiAvi of Ncav Zealand (Apteryx aiidraUs) in the near 

 future, for though it has so far escaped the arroAA^s of the aborigines, 

 it is not likel}^ in its Avingless condition to be able to hold out long 

 against European guns, unless close times and preserved forests are 

 instituted for it, as they have been for our chamois. 



Ea'cu sadder from the biologist's point of a^Icaa^ than such exter- 

 mination of indiA'idual species through tlie Aandalism and greed of our 

 OAvn race is the disturbance of Avhole societies of animals and plants 

 by man that is going on or has been accomplished on most of the 

 oceanic islands, and Ave must briefly notice these cases Avhile Ave are deal- 

 ing Avith the decadence of species. I refer to the croAvding out of the 

 usually endemic animal and plant population on such islands through 

 cultivation. The first step in this Avork of ' cultiA^ation ' is alAA^ays the 

 cutting down of the forests Avhich for thousands of j^ears haA'e clothed 

 these islands as Avith a mantle of green, haA^e regulated their rainfall, 

 secured their fertility, and allowed a medley of indigenous animals, 

 usually peculiar to the spot, to arise. We have already spoken of 



