192 FROM FISH TO PHILOSOPHER 



The centipede was happy quite 



Until a toad in fun 

 Said, *'Pray, which leg goes after which?" 

 That worked her mind to such a pitch. 

 She lay distracted in a ditch. 



Considering how to run.^ 



The difference between the toad and the centipede is 

 that, rhetorically at least, the toad can think and ask 

 questions. Among the notable features that distinguished 

 the Peimsylvanian Amphibia from their cousins among 

 the air-breathing fishes was an increased capacity to con- 

 sider how and why to run. The eyes, now adapted for 

 looking through air instead of water, cotJd survey a 

 greatly widened world across which the feet might carry 

 them from here to there; and the brain could not only 

 dictate the sequence of movements of the legs but it 

 could integrate new sensory information into the total 

 operation and, above all, retain a more complicated rec- 

 ollection and better forecast the consequences of going 

 from here to there. But the emergence of the Amphibia 

 from the water did not represent the 'emergence' of 

 something quahtatively new in respect to brain func- 

 tion: the ostracoderms, the sharks, the air-breathing 

 fishes before them, the reptiles, birds, and mammals 

 after them, all had need of, and all possessed, some 

 measure of awareness of themselves and their environ- 

 ment, and a corresponding ability to react accordingly. 



A man can learn more than a toad, and a toad more 

 than a centipede, because of differences in the degree 

 of elaboration of the brain. In chemical composition, 

 metabolic rate and anatomical structure, the brain of 

 man, the toad, and the centipede do differ in details, 

 but differences in learning capacity and in behavior must 

 be sought not so much in these quahtative differences 

 as in the sheer nimiber of nerve cells and the potential 

 variety of their interconnections. It is said that under 



1 Pinafore Poems 1871. 



