EVOLUTION 915 



acquired forms or propensities are transmitted to their posterity." 

 Thus Erasmus Darwin is nearer to Lamarck than to Buffon. 



Lamarck (1744-1829) was scientifically much more important than 

 Buffon or Erasmus Darwin, but we are here following a chronological 

 order. He was a learned botanist and zoologist, with an enthusiasm 

 which a terribly keen struggle for existence never conquered ; he had 

 no small success in orderly classification — of Invertebrate animals 

 in particular; he had a restlessly speculative mind, more philosophical 

 or synoptic than his two great predecessors. Lamarck's Philosophie 

 Zoologique was described by Haeckel as "the first connected and 

 thoroughly logical exposition of the Doctrine of Descent"; and to 

 that must be added that the suggestiveness of Lamarck's particular 

 theory of evolutionary change has not yet been exhausted. New 

 surroundings evoke new needs, and new needs involve new functions 

 or habits. "Such and such parts, formerly less used, are now more 

 frequently employed, and in consequence become more highly 

 developed; new parts also become insensibly evolved in the creature 

 by its own efforts from within. These gains or losses of organic 

 development, due to use or disuse, are transmitted to offspring, 

 provided they have been common to both sexes, or to the animals 

 from which the offspring are descended." These two propositions, 

 translated by Samuel Butler from the Philosophie Zoologique, are 

 fundamental, yet they are not quite adequate. For at times Lamarck 

 makes it clear that the new need ("besoin") which makes itself felt 

 may be something subtler than increased appetite seeking satisfac- 

 tion, subtler than increased energy seeking vent; it may be definitely 

 psychical — the animal's "bent bow", its endeavour after well-being, 

 its urge towards self-expression. Lamarck's causal theory of evolu- 

 tionary change was thus not only biological, it was psychobiological ; 

 and to this more unified view of life, his critics, usually of strictly 

 physiological and morphological outlook, necessarily fail to do 

 justice, as in so commonly reducing his doctrine to little or nothing 

 more than a naive faith in the transmission of acquired characters. 



ILLUSTRATION OF EVIDENCES OF ORGANIC 



EVOLUTION 



LOGICAL POSITION OF THE IDEA OF ORGANIC EVOLU- 

 TION. — According to the general idea of Organic Evolution, which 

 Darwin so fully brought into intellectual currency, our present-day 

 fauna and flora have arisen by natural processes out of an antecedent 

 fauna and flora, on the whole somewhat simpler and more generalised, 

 and so on backwards through the ages until we lose clue after clue, 

 and find ourselves in the thick mist of life's beginnings. While there 

 have been occasional retrogressions and degenerations, and many 



