Chap, v.] ANALOGOUS VARIATIONS. 203 



have just seen that in several species of the horse-genus 

 the stripes are either plainer or appear more commonly 

 in the young than in the old. Call the breeds of 

 pigeons, some of which have bred true for centuries, 

 species; and how exactly parallel is the case with that 

 of the species of the horse-genus! For myself, I venture 

 confidently to look back thousands on thousands of gen- 

 erations, and I see an animal striped like a zebra, but 

 perhaps otherwise very differently constructed, the com- 

 mon parent of our domestic horse (whether or not it be 

 descended from one or more wild stocks) of the ass, the 

 hemionus, quagga, and zebra. 



He who believes that each equine species was inde- 

 pendently created, will, I presume, assert that each 

 species has been created with a tendency to vary, both 

 under nature and under domestication, in this particular 

 manner, so as often to become striped like the other 

 species of the genus; and that each has been created 

 with a strong tendency, when crossed with species in- 

 habiting distant quarters of the world, to produce hy- 

 brids resembling in their stripes, not their own parents, 

 but other species of the genus. To admit this view is, as 

 it seems to me, to reject a real for an unreal, or at least 

 for an unknown, cause. It makes the works of God a 

 mere mockery and deception; I would almost as soon 

 believe with the old and ignorant cosmogonists, that fos- 

 sil shells had never lived, but had been created in stone 

 so as to mock the shells living on the sea-shore. 



Summary. — Our ignorance of the laws of variation is 

 profound. Not in one case out of a hundred can we 

 pretend to assign any reason why this or that part has 

 varied. But whenever we have the means of instituting 

 a comparison, the same laws appear to have acted in 



