18* THE THEORIES OF EVOLUTION 



gument in favor of discontinuous variation and of De 

 Vries' mutation theory. 



For the exponents of the Lamarckian tendencies, 

 Mendel's laws present a special interest. In a book 

 published recently, "La Crise du transfonnisme," Le 

 Dantec, the most orthodox of French Lamarckians, 

 examines in detail the theory of mutation and devotes 

 a chapter to inheritance as presented by Mendel. His 

 main contention is that the continuity of evolution is 

 the central point of transformism. He opposes reso- 

 lutely the idea of representative particles and the 

 Weismannian hypotheses. The Mendelian experi- 

 ments, however, point to discontinuous variations and 

 to characters which act apparently like real entities. 

 Le Dantec interprets these facts as follows: "There 

 are in every individual, two kinds of characters : first, 

 mechanical, essential, or adaptive characters, necessary 

 to life which result from a slow evolution and do not 

 in any way confirm Weismann's theories. The other 

 category of characters comprises ornamental charac- 

 ters, peculiarities of form, which may be ruled by 

 different laws. The latter are without any impor- 

 tance as regards the evolution of the species. It is to 

 this category that all the Mendelian characters belong 

 and Mendelian cases are not universal but exceptional. 



"In these exceptional cases, characters are really 

 represented by some concrete element and there is a 

 real discontinuity. But this discontinuity is due to 



