AN HISTORICAL SKETCH 



OF THE PROGRESS OF OPINION ON THE ORIGIN 



OF SPECIES, 



PKEVIOUSLT TO THE PUBLICATIOJT OP THE FIRST EDITIOK 



OF THIS WOEK. 



I WILL here give a brief sketch of the progress of opin- 

 ion on the Origin of Species. Until recently the great 

 majority of naturalists believed that species were immut- 

 able productions, and had been separately created. This 

 view has been ably maintained by many authors. Some 

 few naturalists, on the other hand, have believed that 

 species undergo modification, and that the existing forms 

 of life are the descendants by true generation of ])re exist- 

 ing forms. Passing over allusions to the subject in the 

 classical writers,* the first author who in modern times 



*Aristotle, in liis " Pliysicae Auscultationes " (lib. 2, cap. 8, s. 2), 

 after remarking that rain does not fall in order to make tlie corn 

 grow, any more than it falls to spoil the farmer's corn when threshed 

 out of doors, applies the same argument to organization; and adds (as 

 translated by Mr. Clair Grece, who first pointed out the passage to 

 me), '' So what hinders the different parts [of the body] from having 

 this merely accidental relation in nature ? as the teeth, for example, 

 grow by necessity, the front ones sharp, adapted for dividing, and the 

 grinders flat, and serviceable for masticating the food; since they 

 were not made for the sake of this, but it was the result of accident, 

 Afi f] in like manner as to other parts in which there appears to exist 

 an adaptation to an end. Wheresoever, therefore, all things 

 together (that is all the parts of one whole) happened like as if they 

 were made for the sake of something, these were preserved, having 

 been appropriately constituted by an internal spontaneity, and what- 

 soever things were not thus constituted, perished and still peri.'=;h." 

 We here see the principle of natural selection shadowed forth, but 

 how little Aristotle fully comprehended the principle, is shown by 

 his remarks on the formation of the teeth. 



