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, ..... 1 1-30 



The first or heterotypic mitosis, ..... 11-26 



Resting nucleus and the development of the chromatin 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, 67 



Sporodinia, ....... 7* 



Closterium and Cosmarium, . 71 



Diatoms (Rhopalodia, Cocconeis), . . 73 



Basidiobolus, ...... .76 



