114 VARIATION 



In the same general manner, color is likely to fail, and nothing 

 is more common in nature than albino varieties. Thus we have 

 our white currant, strawberry, raspberry, and even the black- 

 berry, almost every thicket affording its examples and speak- 

 ing eloquently of the freedom with which nature creates new 

 forms, and if we will only open our eyes to see what is going on 

 about us, we shall learn much of how it is done. 



Albinism among animals is even more common than among 

 plants. Men, dogs, cats, horses, cattle, sheep, bears, rabbits, 

 rats, mice, and many other species are distinguished by albino 

 varieties. 



These distinctions, marked though they are, arise doubtless 

 from the simplest causes. For example, if an animal for any 

 reason fails to secrete pigment in the normal manner it is from 

 necessity an albino, and if the failure is hereditary an albino 

 race is likely to be established, although unrestricted breeding 

 greatly reduces its probability through crossing with other forms. 



SECTION III EXPERIMENTS OF DE VRIES 1 



Hugo De Vries, professor of botany in the University of 

 Amsterdam, long ago became convinced that Darwin's theory 

 of the origin of species through the gradual accumulation of 

 fortuitous variations is not the only means of creating new types. 

 Darwin taught not only that existing types had been preserved 

 by selection because they in some way fitted the conditions of 

 life, but that the intervening spaces between species and varieties 

 represent extinctions through the agency of natural selection. 



De Vries came to believe that, in many cases at least, the new 

 type springs suddenly from the old, without gradation and without 

 intervening forms, and that while selection may shape up the 

 new type and perhaps the better fit it for existence, yet the 

 selective process is in no way responsible for its origin. Indeed, 

 one of the earliest evidences, to his mind, that new types often 

 arise without the agency of selection, was the notable fact that 

 new forms arising spontaneously in nature are for the most 



1 Hugo De Vries, Species and Varieties, their Origin by Mutation [Open Court 

 Publishing Company, Chicago]. 



