CONTENTS. 



CHAPTER I. INTRODUCTION. 



PAGE. 

 Nuclear division, ........ 2-30 



Karyokinesis in cells of the lower plants in which centrospheres are 

 developed, ....... 2-10 



Dictyota, ....... 2 



Erysiphe, ....... 7 



Mitosis in pollen mother-cells, ... . 11-30 



The first or heteroty pic mitosis, ..... 11-26 



Resting nucleus and the development of the chromatm spirem 1 1 

 Development of the spindle, . . . . 15 



Chromosomes, ....... 17 



Metakinesis, ...... 20 



The anaphase, ....... 22 



The telophase, ...... 23 



The nucleolus, ....... 25 



The second, or homotypic division, .... 27-31 



Cell division, ....... 31-44 



The type of the higher plants, . . . . . 31 



Free cell-formation, . . . . -33 



Cell-cleavage, ....... 36 



Cell-division in Dictyota and Stypocaulon, . . . .41 



The centrosome and the blepharoplast, .... 44 



The significance of the sexual process and the numerical reduction of 

 the chromosomes, ....... 49-60 



CHAPTER II. FECUNDATION; MOTILE ISOGAMETES. 



Ulothrix and Hydrodictyon, . . . 61-65 



Copulation of gametes, . . 65 



Ectocarpus, 65 



CHAPTER III. FECUNDATION ; NON-MOTILE ISOGAMETES. 



Spirogyra, 



Sporodinia, ..... 



Closterium and Cosmarium, . 71 



Diatoms (Rhopalodia, Cocconeis), . 73 



Basidiobolus, 



v 



