CONTENTS. 



§8. "Body" versus reproductive cells, and the continuity 

 of the latter. 



Owen. 



Hi-eckel.' 



Rauber, 



Brooks. 



Jager. 



Galton. 



Nussbaum. 

 § 9. Weismann's theory of the continuity of the germ-plasma. 



CHAPTER VIII. 

 The Egg-Cell OR Ovum ..... 97-108 



§ I. Structure of ovum — 



Cell-substance and protoplasm. 

 Nucleus and chromatin. 



§ 2. Growth of ovum — 



Transition from amceboid to encysted phase. 



§ 3. The yolk- 

 Its threefold mode of origin. 

 Its diftuse, polar, or central disposition. 

 Resulting influence on segmentation, 



§ 4. Composite ova. 



§ 5. Egg-envelopes — 



{a.) From o\aim itself. 



{h. ) From surrounding cells. 



[c. ) From special glands. 



§ 6. Birds' eggs- 

 Concrete illustration of facts and problems. 



§ 7. Chemistry of the o\aim — 



Its capital of anastates. 



§ 8. Maturation of ovum — 



Occurrence, formation, history of polar globules ; 

 parthenogenetic ova. 



§ 9. Theories of polar globules — 



1. ^linot, Balfour, Van Beneden, <S:c. 



2. Biitschli, Hertwig, Boveri, &c. 



3. Weismann. 



CHAPTER IX. 



The Male-Cell OR Sperm . . - - . 109-116 



§ I. General contrast between sperm and ovum — 



An index to contrast between male and female. 



§ 2. History of discovery — 



(a.) Hamm and Leuwenhoek. 



\b.) Animalculists. 



(r.) Classed as Entozoa or parasites, 



{d.) KoUiker's demonstration of cellular origin. 



