46 PERIOD II. 



Hydra a link between plants and animals, the snails and 

 slugs a link between mollusca and serpents, flying- 

 fishes a link between ordinary fishes and land verte- 

 brates, the ostrich, bat, and flying fox links between 

 birds and mammals. Man, endowed with reason, 

 occupies the highest rank; then we descend to the 

 half-reasoning elephant, to birds, fishes, and insects 

 (supposed to be guided only by instinct), and so to the 

 shell-fish, which shade through the zoophytes into 

 plants. The plants again descend into figured stones 

 (fossils) and crystals. Then come the metals and demi- 

 metals, which are specialised forms of the elemental 

 earth. Water, air, and fire, with perhaps the asther of 

 Leibnitz, are placed at the bottom of the scale. 



In Bonnet's hands the scale of nature became an 

 absurdity, by being traced so far and in so much detail. 

 It was not long before a reaction set in. The great 

 German naturalist, Pallas, in his Elenchus Zoophytorum 

 (1766) showed that no linear scale can represent the 

 mutual relations of organised beings ; the branching 

 tree, he said, is the appropriate metaphor. Cuvier 

 taught that the animal kingdom consists of four great 

 divisions which are not derived one from another, and 

 his authority overpowered that of Lamarck, who still 

 maintained that all animals form a single graduated 

 scale. A complete reversal of opinion ensued, so com- 

 plete that at length the theologians, who had once seen 

 in the scale of nature a proof of the wisdom of Provi- 

 dence, were found fighting with all their might against 

 the insensible gradations which, according to Darwin's 

 Origin of Species, must have formerly connected what 

 are now perfectly distinct forms of life. 



The eighteenth-century supporters of continuity in 

 nature were not merely wrong in picturing the organised 



