CONTENTS. Vll 



BOOK II.— ANALYSIS OF SEX— ORGANS, TISSUES, 



CELLS. 



CHAPTER V. 



PAGE 



Sexual Organs and Tissues ------ 51-59 



I. Essential sexual organs of animals. 



II. Associated ducts. 



III. Origin of yelk-glands, &c. 



IV. Organs auxiliary to impregnation. 

 V. Egg-laying organs. 



VI. Brood-pouches. 



CHAPTER VI. 



Hermaphroditism _■_._--. 60-76 



I. Definition of hermaphroditism ; its varied forms. 

 II. Embryonic hermaphroditism. Ploss, Laulanie, Sutton. 



III. Casual or abnormal hermaphroditism, from jelly-fish to 



mammal. 



IV. Partial hermaphroditism, from butterflies to birds. 



V. Normal adult hermaphroditism, from sponges to toads. 

 VI. Degrees of normal hermaphroditism. 

 VII. Self-fertilization and its preventives. 

 VIII. Complemental males — cirripedes and Myzostomata. 

 IX. Conditions of hermaphroditism ; its association with. 



passivity and parasitism. 

 X. Origin of hermaphroditism ; the primitive condition ; 

 persistence and reversion. 



CHAPTER VII. 



The Sex-Elements (General and Historical) - - - 77-91 



I. The ovum-theory. 



II. The history of embryology, "evolution" and "epigenesis." 

 Harvey's epigenesis and prevision of ovum- 

 theory. 

 Malpighi and early observers. 

 Preformation school ; " evolution " according to 

 Haller, Bonnet, and Buffon ; ovists and ani- 

 malculists. 

 Wolff's demonstration of epigenesis. 

 Wolff's successors. 



III. The cell-theory. 



IV. The protoplasmic movement. 



V. Protozoa contrasted with Metazoa ; the making of the 



"body." 

 VI. General origin of the sex-cells in sponges. 



" " " " ccelenterates. 



other Metazoa. 

 VII. Early separation of the sex-cells in a minority of cases. 



