168 THE SCIENCE OF BIOLOGY 



The ideas of Jean Baptiste, Chevalier de Lamarck (1744- 

 1829) were a natural development from the evolutionary 

 concepts of Buffon. Lamarck was primarily a man of 

 science rather than a philosopher. He is usually regarded as 

 the founder of modern invertebrate anatomy. However 

 much one may be disinclined to accept the Lamarckian 

 doctrine, its originator was an active investigator. He is, 

 therefore, not open to the charge of having been a specula- 

 tive philosopher rather than a scientist. 



Historically, the importance of the Lamarckian hypothe- 

 sis is found in the fact that it was the first comprehensive 

 formulation of the causes of the evolutionary process. Lamarck 

 accepted evolution as an historical fact. He proposed his 

 theory of the inherited effects of use and disuse and of the en- 

 vironment, as an explanation of the causes of evolution. 13 



The gist of the Lamarckian theory is that the individual is 

 modified by the use and the disuse of its parts and that these 

 modifications are transmitted to its descendants. The case 

 is similar with the effects of the environment. An animal 

 which runs develops the parts involved. It runs faster with 

 practice and it has stronger and larger muscles after many 

 repetitions of this activity, just as does the athlete who has 

 undergone prolonged training. The adage " practice makes 



Lamarck was a product more distinctive of the eighteenth than of the nine- 

 teenth century. Lamarck's ideas represent the climax of the transmutationist 

 doctrines. Moreover, the more active working years of his life (1744-1829) 

 fall within the eighteenth century. 



13 There exists in non-scientific circles at the present day a confusion between 

 evolution as an historical process and the causes which have produced evolu- 

 tion. This is frequently seen in the confusion between the Darwinian theory 

 of Natural Selection, which is a theory of the causes of evolution, and the more 

 comprehensive doctrine of organic evolution. The historical fact of evolution 

 is as distinct from its causes as the historical fact of the colonization of the 

 western hemisphere by Europeans is distinct from the causes which have in- 

 duced so many people to leave Europe during the past four hundred years. 

 The fact that the Americas were thus settled is beyond reasonable question. 

 The causes of this migration westward of Frenchmen and Englishmen and 

 Spaniards and later Germans, Irish, Italians, and the like are a different matter 

 and one concerning which there exist divergences of opinion. 



