1010 



sideration, he must see that the production of hybrids between indi- 

 viduals of different genera, orders and classes, is rendered impossible 

 by the difference of the structure of such plants preventing fecunda- 

 tion ; only those plants and animals that most nearly approach each 

 other in structure, being capable of engendering together. But it is 

 stated on high authority, that hybrids have been procured between 

 individuals of different genera. Thus Treviranus describes a hybrid 

 between Campanula divergens and Phyteuma betonicsefolia ; Gaert- 

 ner, one from Convolvulus sepium fecundated by Ipomcea purpurea, 

 from Datura Isevis and Metel fecundated by the henbanes and tobac- 

 co, from Glaucium luteum fecundated by the poppies, &c. ; Wieg- 

 mann also obtained hybrids from Vicia faba fecundated by Ervum 

 lens, and from Pisum arvense by Vicia sativa ; lastly. Knight fecun- 

 dated the almond with the pollen of the peach.* 



Mr. Edmonston has admitted, in his former communication, that 

 genera, orders and classes are pure abstractions, for he has said that 

 Nature only creates species ; but we have here two of these abstrac- 

 tions (in a certain sense) copulating and bringing forth hybrids. 

 What has now become of his argument derived from hybridity ? 



But Mr. Edmonston further says ; " It is obvious to every unpre- 

 judiced mind, that Nature has created individuals having certain com- 

 mon peculiarities which no other induction from individuals possesses, 

 and to these we give the name of species." I am afraid that this is 

 as unintelligible to me, as my statement of the two senses in which 

 groups are natural appears to be to Mr. Edmonston; but coupling it 

 with the following sentence from Mr. E.'s letter, we shall find that 

 even he allows, after all, that " species " is an induction or abstraction, 

 for the terms are synonymous. '' The word species implies a conge- 

 ries of individuals having certain common peculiarities and distinc- 

 tions ; and when we say that Nature creates species, we mean that she 

 creates individuals having the properties which we attribute to the 

 abstraction — species." This settles the question as regards species 

 between Mr. Edmonston and myself; and unless Mr. Forster has 

 something more to bring forward on the subject, the matter must be 

 considered as finally adjusted, for Mr. Edmonston has fully, but pro- 

 bably unintentionally, admitted all that I could desire. I certainly 

 did not expect to proselytize him so quickly, and I congratulate him 

 on arriving at the only sense in which the term is applicable to the 

 three kingdoms of Nature. 



* DeCandolle, Pliysiologie, tome ii. p. 703. 



