OPGANIC EVOLUTION 



269 



40 



36 



32 



28 



-4 



20 



lu 



12 



■-.Tipw^yjww^g; 



[ "■"g. ' iaa 



^ 

 ^ 



^ 



Fig. 164. One hundred rag weed seeds arranged in classes according to the 

 number of their spines. The Hne represents their curve of variation. 



