CHAPTER VIII. 



CLASSIFICATION OF THE FORMS OF THE PRINCIPLES 

 PRODUCING ALLOGAMIC EVOLUTION. 



I. Tables op Forms, with Brief Explanations 



The analysis presented in the two preceding chapters has revealed 

 many factors, which are here brought together in tables so arranged 

 as to show the more important of their relations to each other. (See 

 pages 138-139.) 



1. Allogamic, Autogamic, and Agamic Evolution. 



A complete classification of the factors of organic evolution must 

 include the principles producing differentiation of organisms multi- 

 plying asexually, as well as of those reproducing sexually. Moreover, 

 the reproduction of self-fertilizing species is so unlike that of species in 

 which cross-fertilization takes place (either in each generation or at 

 the end of a series of generations), that it seems necessary to consider 

 their methods of transformation separately. Following these dis- 

 tinctions, organic evolution needs to be divided into three depart- 

 ments, which may be called : 



Allogamic evolution, which relates to the evolution of cross-fertiliz- 

 ing organisms ; 



Autogamic evolution,* which relates to the evolution of self -fertil- 

 izing organisms ; and 



Agamic evolution, which relates to the evolution of organisms 

 whose reproduction is continuously asexual. 



The investigation presented in this volume relates to allogamic 

 evolution. 



* Karl Pearson, in 2nd ed. of "The Grammar of Science," London, 1900, p. 423, 

 uses the term "Autogamic Mating" to designate self-fertilization. 



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