The Making of Species 
sport. Similarly, white animals appear not to 
give rise to colour varieties. 
We are never surprised to find that an ordi- 
nary upright plant produces as a sport or muta- 
tion a pendulous, or fastigiate form. These 
aberrant varieties, be it noted, occur in species 
which belong to quite different orders. 
De Vries points out that laciniated leaves 
appear in such widely separated trees and shrubs 
as the walnut, the beech, the hazel-nut, and the 
turnip. 
Another example of the definiteness of varia- 
tion is furnished by what Grant Allen calls the 
“Law of Progressive Colouration ” of flowers. 
On pp. 20, 21 of Zhe Colours of Flowers, 
he writes, “ All flowers, as we know, easily sport 
a little in colour. But the question is, do their 
changes tend to follow any regular and definite 
order? Is there any reason to believe that the 
modification runs from any one colour toward 
any other? Apparently there is. . .. All 
flowers, it would seem, were in their earliest 
form yellow ; then some of them became white; 
after that a few of them grew to be red or 
purple ; and finally a comparatively small number 
acquired the various shades of lilac, mauve, violet, 
or blue.” 
So among animals there are many colour 
patterns and structures that appear in widely 
different genera, as, for example, the magpie 
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