Preface vii 



is avowedly not exact in some of the details; (2) it is 

 adapted definitely to young botanists with fairly thor- 

 ough elementary training. The excuse for the inexact- 

 ness of certain details is the pedagogical necessity. The 

 preparation of a text for the students referred to is 

 explained by the fact that it represents a very important 

 group which has not been provided for. In brief, the 

 book is neither a technical presentation of genetics nor a 

 general text, but a course of general lectures adapted to 

 a special purpose. 



In connection with the laboratory phase of this course 

 the authors wish to make grateful acknowledgment to 

 E. M. East, Albert Blakeslee, R. A. Emerson, and 

 G. H. Shull for very useful illustrative material. 



J. M. C. 

 M. C. C. 



