26 WHAT EVOLUTION IS 



and by a row of bones which repre- 

 sent the middle finger of man. These 

 bones in man are four in number, 

 counting the deep-seated long bone 

 in the palm, and this number is ex- 

 actly reproduced in the horse, in which 

 the last member of the series carries 

 the hoof corresponding to the human 

 nail. The front leg of the horse not 

 only rests on what is equivalent to 

 the enormously enlarged middle fin- 

 ger of man, but it contains, on either 

 side of this digit, relatively inconspic- 

 uous splint bones which represent our 

 index and our ring fingers. 



By the comparative method it is 

 thus possible to demonstrate that 

 such apparently diverse organs as the 

 arm of a man, the wing of a bat, and 

 the foreleg of a horse are similarly 

 organized and are merely modifica- 

 tions of one type of structure. 



Animals and plants abound on 



