186 The Origin of Species by Mutation. 



the origin of species but with the development of specific 

 characters. 



The diversity of organic forms is due to the existence 

 of a vast number of differentiating characters. And the 

 question we have to answer is ''how have these characters 

 arisen?" 



Subspecies become species by extinction of inter- 

 mediate forms. New species can arise by crossing when 

 the pecuHarities of two forms already existing are united 

 to form a single new one ; and so on. But these are not 

 cases of the origin of specific characters. Many species 

 and even genera and still larger systematic groups have 

 arisen by these characters disappearing or becoming la- 

 tent. The origin of the monocotyledons from the dicoty- 

 ledons is regarded by some as coming under this head 

 (Delpino). But loss and latency are obviously special 

 cases which do not directly touch the main question of 

 progress in the animal and vegetable kingdom. 



The question is not how m.any characters peculiar to 

 itself must an animal or plant possess to justify its ele- 

 vation to specific rank, but : how have these characters 

 arisen, or how can they arise ?^ 



In other w^ords : the mutation and the actual process 



of mutating must become the object of investigation. 



And if we once discover the nature of this process, not 



only will our insight into the actual relationship of living 



organisms become much deeper, but w^e may even hope 



that we may be able to gain some measure of control over 



the formation of species. If the breeder has obtained 



control over variability why should he not obtain it over 



mutation as well ? 



^ "These factors are the units with which the science of heredity 

 has to deal." Intracell. Pangenesis, p. 9. For their association in 

 groups see pp. 21-22 and ZZ- 



