10 The Significance of Horticultural Varieties. 
tendency to become fixed and so to become races : in the 
same way these races would later be transformed into 
species. This is the generally accepted view. 
This view is based, as I attempted to show in the first 
part of the first volume, on an unwarranted extension 
of DARWIN'S theory of selection. DARWIN argued from 
the results obtained in horticulture ; but these, at least as 
described in the works of the best authorities, do not 
seem to me to justify such an extension. 
According to the prevailing view, man has the power 
to produce any desired amelioration in any species ready 
to hand. All characters vary and all that need be done 
would be to isolate the extreme variants and to breed 
further from them. The process takes some time of 
course but in many species the experiment is already 
lasting about half a century. But the advances which 
have been made, and which are of the very greatest prac- 
tical importance, do not tally with this assumption. On 
the contrary we learn from them that for much that has 
been attained much has proved unattainable. 
The comparative studies of systematists show us that 
almost everywhere there exist imperceptible transitional 
stages between the smallest differences and perfectly dis- 
tinct species. This forms a weighty argument for, but 
no proof of, the prevalent view. For we have to reckon 
here with transgressive variability (Vol. I, Part II, 25, 
p. 430), which tends to blur the boundaries of related 
groups. 
I have indicated in the foregoing section (1) the 
principles on which in my opinion an elucidation of the 
process in question must be based. If a small anomaly 
is found in a wild or cultivated species, and a new and 
constant form is raised from this by selection, the whole 
