AMONG THE GREEKS 71 



losophy and begins many of his treatises with a 

 history of opinion, after the modern German 

 fashion. In his Physics are found the greater part 

 of his interpretation of Nature and his discovery 

 of previous interpretations by his Greek prede- 

 cessors. He frequently quotes and discusses the 

 opinions of Empedocles, Parmenides, Democri- 

 tus, Herachtus, Anaxagoras, and others. 



Let us first look at Aristotle's rare breadth as 

 a naturahst. He enters a plea for the study and 

 dissection of lower types: "Hence we ought not 

 with puerile fastidiousness to neglect the contem- 

 plation of more ignoble animals; for in all ani- 

 mals there is something to admire because in all 

 there is the natural and the beautiful." He dis- 

 tinguished five hundred species of mammals, 

 birds, and fishes, besides exhibiting an extensive 

 knowledge of polyps, sponges, cuttlefish, and 

 other marine forms of life. His four essays upon 

 the parts, locomotion, generation, and vital prin- 

 ciple of animals, show that he fully understood 

 adaptation in its modern sense ; he recognized the 

 analogies if not the homologies between different 

 organs like the limbs; he distinguished between 

 the homogeneous tissues made up of like parts 

 and the heterogeneous organs made up of unlike 

 parts; he perceived the underlying principle of 

 physiological division of labor in the different or- 

 gans of the body; he perceived the unity of plan 



