4 The Significance of Horticultural Varieties. 
The development of the statistical treatment of varia- 
tion which took place after DARWIN'S time, allows of an 
altogether different conception of the phenomena than 
was possible some fifty years ago. It was shown that 
the fluctuation of characters is due to their development 
to a greater or less degree. But the character in ques- 
tion does not vary in any other than these two directions. 
The variation is linear (Vol. I, p. 118). It increases 
or diminishes but creates nothing new. New characters 
can arise, so to speak, alongside of it, but they arise 
independently of the fluctuation of the old ones. 
This applies to the case before us. The variations 
which the horticulturist looks for and then works up 
are not variations of the old characters', such may indeed 
give rise, by selection, to improved races, but not to 
new types (Vol. I, p. 82). The required deviations are 
anomalies, as in the example of the origin of double 
flowers, just cited. When such an anomaly arises we may 
be sure that the new character already existed in the 
internal organization of the plant. Where it springs 
from and how it arose is a matter of indifference to the 
breeder : he has got it and can work it up. In other 
words : ' 'The first condition necessary for raising a nov- 
elty is to possess it" (Vol. I. p. 185). , 
In this connection two cases are distinguished in prac- 
tice according as one is dealing with apparently invariable 
forms, or with forms exhibiting a high degree of fluctu- 
ating variability. In the former case all that has to be 
done is to isolate the novelty and to free it of possible 
impurities introduced by crossing. If this can be done 
without much difficulty the variety is perfect and con- 
stant from the beginning and needs only a few years of 
multiplication before it can be put on the market (Vol. 
