Aim and Method of Comparative Anatomy 361 



Fig. 289. Skeletons of horse and man. Corresponding skeletal parts are mounted 

 in approximately parallel alignment. (Courtesy, American Museum of Natural 

 History, New York.) 



erly be applied to correspondence in function. But when a certain 

 organ in one animal is the same organ as that in another animal, the 

 relation demands a word signifying "sameness." Such a word is "ho- 

 mology," from the Greek word meaning "identical." The tail-fin of a 

 fish and the screw-propeller of a motorboat are analogous, both being 

 mechanisms of propulsion. But they are not homologous. 



The word "homology" had been used in anatomy before Owen's 



