CONTINUITY OF THE GERM-PLASM, &c. 



PREFACE. 



THE ideas developed in this essay were first expressed during 

 the past winter in a lecture delivered to the students of this Uni- 

 versity (Freiburg), and they were shortly afterwards in February 

 and the beginning of March written in their present form. 

 I mention this, because I might otherwise be reproached for a 

 somewhat partial use of the most recent publications on related 

 subjects. Thus I did not receive Oscar Hertwig's paper ' Contri- 

 butions to the Theory of Heredity ' (Zur Theorie der Vererbung), 

 until after I had finished writing my essay, and I could not there- 

 fore make as much use of it as I should otherwise have done. 

 Furthermore, the paper by Kolliker on ' The Significance of the 

 Nucleus in the Phenomena of Heredity ' (Die Bedeutung der Zell- 

 kerne fur die Vorgange der Vererbung), did not appear until after 

 the completion of my manuscript. The essential treatment of the 

 subject would not, however, have been altered if I had received the 

 papers at an earlier date, for as far as the most important point the 

 significance of the nucleus is concerned, my views are in accord- 

 ance with those of both the above-named investigators ; while the 

 points upon which our views do not coincide had already received 



attention in the manuscript. 



A. W. 



FKEIBDEG i. BREISGAU, 

 June 16, 1885. 



