Chap. V.J ANALOGOUS VAKIATIONS. 203 



And we 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 generations, and I see an animal striped 

 like a zebra, but perhaps otherwise very differently 

 constructed, the common 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 

 independently 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 

 inhabiting distant quarters of the world, to produce 

 hybrids 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 fossil 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 



