422 STERILITY OF HYBRIDS. 



the Selection of the Plutocrats and land-holders), says, 

 in an article in No. LII, of the Popular Science Monthly: 



"What is needed for the completion of Darwin's 

 theory of the origin of species, is, first, definite proof 

 that selective breeding is competent to convert perma- 

 nent races into physiologically distinct species." 



As the reader has already been shown, the very 

 antithesis to such proof is to be found in Darwin's 

 facts. Darwin's facts show, that such definite proof, 

 as Huxley requires, is absolutely impossible ever to be 

 supplied. These demonstrate, that selective breeding 

 (so far as it has any effect) endows permanent races 

 with a physiological character, more and more unlike 

 that of distinct species, inasmuch as it makes the indi- 

 viduals of each such race, sterile inter se (i. e. with 

 other individuals of the same race), and gives them an 

 increase of fertility and of constitutional vigor, when 

 they are crossed with individuals of other races of the 

 same species : a result, the direct converse of the char- 

 acter marking distinct species, whose individuals are, 

 in the main, fertile with the individuals of their own 

 species, and sterile with individuals of other species. 



As has been mentioned, Huxley further says : 



"What is needed for the completion of Darwin's 

 theory, is, * * * secondly, the elucidation of the 

 nature of variability." 



Darwin's facts show, also, that there is an elucidation 

 of the nature of variability ; but such elucidation, equally 

 with the solution of the physiological problem, militates 

 against Darwin's theory, inasmuch as it shows, that 

 there is a definite limit to such variability, and that 



