93 



none was received with more genuine appreciation and honor 

 than Professor de Vries. No more fitting memorial of his sum- 

 mer in America could have been left to his delighted hosts than 

 this series of charming lectures on the most fundamental prob- 

 lems of biology, and one may safely predict that the work will 

 further stimulate the interest that has awakened everywhere in 

 experimental research in variation and heredity, the two funda- 

 mental processes of organic evolution. 



GEORGE HARRISON SHULL. 



STATION FOR EXPERIMENTAL EVOLUTION, 

 COLD SPRING HARBOR, NEW YORK, 

 April, 1905. 



