NATUEAL- SELECTION. 103 



in the struggle for existence and in the principle of natu- 

 ral selection, will acknowledge that every organic being 

 is constantly endeavoring to increase in numbers ; and 

 that if any one being varies ever so little, either in habits 

 or structure, and thus gains an advantage over some 

 other inhabitant of the same country, it wiU seize on the 

 place of that inhabitant, however different that may be 

 from its own place. Hence it will cause him no surprise 

 that there should be geese and frigate-birds with webbed 

 feet, living on the dry land and rarely alighting on the 

 water ; that there should be long-toed corn-crakes, living 

 in meadows instead of in swamps ; that there should be 

 woodpeckers where hardly a tree grows ; that there should 

 be diving thrushes and diving Hymenoptera, and petrels 

 with the habits of auks. 



NO MQDIFICATIOSr IN ONE SPECIES DESIGNED FOE THE 

 GOOD OF ANOTHEK. 



Origin of Natural selection can not possibly produce 



Species, any modification in a species exclusively for 



page . ^j^g good of another species ; though through- 

 out nature one species incessantly takes advantage of, and 

 profits by, the structures of others. But natural selection- 

 can and does often produce structures for the direct in- 

 jury of other animals, as we see in the fang of the adder, 

 and in the ovipositor of the ichneumon, by which its eggs 

 are deposited in the living bodies of other insects. If it 

 could be proved that any part of the structure of any one 

 species had been formed for the exclusive good of another 

 species, it would annihilate my theory, for such could not 

 have been produced through natural selection. Although 

 many statements may be found in works on natural his- 

 tory to this effect, I can not find even one which seems to 



