The essay on "Fertilization and Hybridization" was read in 

 Haarlem in the Dutch language, and appears here in an enlarged 

 form. My conception of the life-processes in the nuclei is chiefly 

 based on the renowned investigations of van Beneden and of Boveri, 

 as well as the most recent researches by Conklin (Contr. Zool. Lab. 

 Pennsylvania, XII, 192), Sutton (Biol. Bull. IV, Dec., 1902), Eisen, 

 (Jour. Morphol XVII, 1), Errera (Revue Scientif. Feb., 1903), and 

 of many others. For the literature I refer to E. B. Wilson, The 

 Cell in Development and Inheritance, and V. Hacker, Praxis und 

 Theorie der Zellen-und Befruchtungslehre. 



My presentation of the processes of fertilization and hybridiza- 

 tion is an outcome of the experiments which I have described in the 

 second volume of my Mutationstheorie (Leipsic, Veit & Co., 1901- 

 1903. English translation by Open Court Publishing Co., 1909-1910.) 



H de V. 



