EVOLUTION 89 



course, as much a characteristic of the snake as the absence 

 of legs. 



Other arguments against the validity of Lamarckism 

 are: first, that no one has ever been able to prove, by ex- 

 periment or otherwise, that the effects of use (the so-called 



FIG. 47. Jean Baptiste Lamarck (1744-1829). He elaborated the 

 hypothesis of organic evolution by inheritance of the effects of use 

 and disuse. 



"acquired characters") are inheritable, while innumerable 

 facts indicate that they are not; second, the hypothesis 

 could apply only to the animal kingdom, since plants in 

 general have no nervous and muscular activities like those 

 of animals. A hypothesis of organic evolution, to be valid, 

 must apply equally to both plants and animals. 



3. Darwin's Hypothesis. This will be outlined in the 

 next chapter. 



