X CONTENTS. 



CHAPTER XII. 



TAGE 



Theory of Fertilization - i47- T 57 



]. Old theories — 



(a) Ovist, (b) animalculists, (r) the "aura 

 semina/is. ' ' 

 II. Modern morphological theories — 



(a) Nuclei all-important. Hertwig, Stras- 

 burger, &c. 



(b) Cell-substance also important. Nussbaum, 

 Boveri, &c. 



<IL .Modern physiological theories — 



Sachs, De Bary, Marshall Ward, &c. 



Cienkowski and Rolph. 



Weismann's view. 



Critique and statement of present theory. 



IV. Use of fertilization to the species — 



(a) Rejuvenescence — 



Van Beneden and Biitschli. 

 Galton and Hensen. 

 Weismann's critique. 



(b) The observations of Maupas. 



(c\ A source of variation. Brooks and Weismann. 



CHAPTER XIII. 



Regenerate Sexual Reproduction or Parthenogenesis 15S-174 



I. History of discovery 

 II. Degrees of parthenogenesis — 



Artificial, pathological, occasional, partial, sea- 

 sonal, total. 



III. Occurrence in animals- 



Rotifers, crustaceans, insects. 



IV. Occurrence in plants — 



Phanerogams and fungi. 



V. The offspring of parthenogenesis. 

 VI. Effects on the species. 



VII. Peculiarities of parthenogenetic ova — 



Weismann's discovery. 

 VIII. Theory of parthenogenesis — 

 Minot and Balfour. 

 Rolph and Strasburger. 

 Weismann. 

 The present. 

 IX. Origin of parthenogenesis. 

 X. Case of bees. 



CHAPTER XIV. 



Asexual Reproduction - - 175^84- 



1. Artificial division. 

 II. Regeneration. 



III. Degrees of asexual reproduction. 



IV. Asexual reproduction in plants and animals. 



