nil CONTENTS. 



CHAPTEE XII. 



General Results. 



Gross-fertilisation proved to be beneficial, and self-fertilisation in- 

 jurious Allied species differ greatly in the means by which 

 cross-fertilisation is favoured and self-fertilisation avoided 

 The benefits and evils of the two processes depend on the degree 

 of differentiation in the sexual elements The evil effects not 

 due to the combination of morbid tendencies in the parents 

 Nature of the conditions to which plants are subjected when 

 growing near together in a state of nature or under culture, and 

 the effects of such conditions Theoretical considerations with 

 respect to the interaction of differentiated sexual elements 

 Practical lessons Genesis of the two sexes Close correspon- 

 dence between the effects of cross-fertilisation and self-fertilisa- 

 tion, and of the legitimate and illegitimate unions of hetero- 

 styled plants, in comparison with hybrid unions Page 439-474 



Indks .. ,. .. .. . .. .. Page 475-487 



