PREFACE i x 



Note 



Less than two months after the completion of the texl of tins book 

 the author has received copies of the two now English works on cytology: 

 W. E. Agar's Cytology, With Special Reference to the M< tazoan NucU us and 

 L. Doncaster's An Introduction to the Study of Cytology. Both deal 

 almost exclusively with animal cytology, the firsl being valuable for 

 its account of chromosome behavior in animals, and the second for its 

 discussions of gametogenesis, fertilization, parthenogenesis, and Bex- 

 determination. These works, together with the botanical portions of 

 the present volume, should make an acquaintance with the general field 

 of cytology much more readily attainable. 



