THE BIOLOGY OF THE ANCIENTS 3 



feet and a complex, ruminating* stomach, and lack the 

 upper incisor teeth ; hollow horns, supported by bony 

 horn-cores, are not shed, but solid horns are shed every 

 year ; birds which are armed with spurs are never 

 armed with lacerating claws ; insects which bear a sting 

 in the head are always two-winged, but insects which 

 bear their sting behind are four-winged. He traces 

 analogies between things which are superficially unlike, 

 such as plants and animals — the mouth of the animal 

 and the root of the plant. The systematic naturalist is 

 prone to attend chiefly to the differences between 

 species ; Aristotle is equally interested in their resem- 

 blances. The systematic naturalist arranges his 

 descriptions under species, Aristotle under organs or 

 functions; he is the first of the comparative anatomists. 

 His conception of biology (the word but not the thing 

 is modern) embraces both animals and plants, ana- 

 tomy, physiology, and system. That he possessed a 

 zoological system whose primary divisions were nearly 

 as good as those of Linnaeus is clear from the names 

 and distinctions which he employs ; but no formal 

 system is set forth in his extant writings. His treatise 

 on plants has unfortunately been lost. 



Aristotle, like all the Greeks, was unpractised in 

 experiment. It had not yet been discovered that an 

 experiment may quickly and certainly decide questions 

 which might be argued at great length without result, 

 nor that an experiment devised to answer one question 

 may suggest others possibly more important than the 

 first. Deliberate scientific experiments are so rare 

 among the Greeks that we can hardly point to more 

 than two — those on refraction of light, commonly 

 attributed to Ptolemy, and those by which Pythagoras 

 is supposed to have ascertained the numerical relations 



