182 EVOL U TION A ND D OGMA . 



consecutive formations, and which falsely appear to 

 have been abruptly introduced. On this view the 

 difficulties above discussed are greatly diminished, or 

 even disappear." ' 



Sterility of Species when Crossed. 



The third objection against Evolution, the last one 

 we shall consider, is based on the sterility of species 

 when crossed and on the infertility of hybrids. The 

 argument as usually advanced appears well-founded, 

 and is, it must be confessed, not without its difficulties. 



According to anti-evolutionists species have been 

 rendered barren by a special provision of nature, in 

 order thereby to prevent confusion which would 

 result from intercrossing. So convinced, indeed, 

 was Frederick Cuvier, the brother of the illustrious 

 paleontologist, of this view, that he did not hesitate 

 to declare: "Without the employment of artificial 

 means or without derogation to the laws of Provi- 

 dence, the existence of hybrids would never have 

 been known." And Dufr^noy affirmed that "animals 

 instinctively mate with individuals of their own 

 species only, and avoid those of others, as they 

 instinctively select food and eschew poison." 



"In fact," writes De Quatrefages, who to the day 

 of his death was opposed to the transmutation 

 theory, " if in the organized world there exists any- 

 thing which ought to strike the superficial observer, 

 it is the order and constancy which we see there 

 reigning during the past ages; it is the distinction 

 which is maintained among those groups of beings 



1 "The Origin of Species," vol. II, p. 88. 



