INTRODUCTION 3 



bees (eggs which produce only drones), of the sound- 

 producing mechanism of the cicada and the grasshopper, 

 of the hectocotylus-arm of some Octopod, of sharks 

 attached to the mother by a kind of placenta, of the 

 early stages of the developing chick, and of many more 

 secrets of nature. It is true that much of his knowledge 

 is drawn from other observers, as words like " it is said," 

 continually remind us, and that hardly any of his stories 

 are perfectly right, but what a range of curiosity they 

 indicate ! We find too abundance of general remarks on 

 structure, valuable because they go just as far as obser- 

 vation extended and no farther, such generalisations as 

 Bacon called " axiomata media," e.g. that horned quadru- 

 peds, with no upper front teeth, ruminate ; that birds 

 which are armed with spurs are never armed with 

 lacerating claws ; that in poultry the eye is closed 

 chiefly by the lower lid, but in owls by the upper lid ; 

 that insects with more than one pair of wings may 

 bear a sting in the tail, but that such a sting is never 

 found in two-winged insects. Aristotle is the real 

 founder of Comparative Anatomy, and perhaps no 

 science ever made so prosperous a start, enriched from 

 its birth with such a multitude, not only of facts but 

 ideas. 



No pilot can explore unsurveyed channels without a 

 confidence which sometimes leads to disaster. The Greek 

 philosophers would have been more than men if they 

 had not often tried to explain things which they very 

 imperfectly understood. Aristotle at least well knew the 

 risks which he ran. " This," he says, " seems to be the 

 mode of generation of bees, as ascertained both by reason 

 and observation. All that takes place is not indeed 

 cleared up ; even if it were, we must rather rely upon 

 observations than reasoning, and rely upon reasoning 



