Increase in Variability in One Direction. 13 
sowings repeated year after year avail nothing if chance 
does not play its part. Anemone coronaria plena arose 
in the nurseries of WILLIAMSON in England as a single 
plant, which exhibited a slight petaloid broadening of one 
of the stamens. 1 From the seed of this specimen a race 
has been started, the flowers of which became fully 
double in the course of a few generations. The double 
varieties of roses, Campanulas, and many other garden 
plants have arisen in the same way. I saw a bed of 
mignonette (Reseda odorata) some of which had double 
spikes, in a nursery at Erfurt. The spikes were fasciated, 
the flowers were broader and the whole plant fuller, more 
compact and handsomer than the species. The plants of 
this bed had been produced from the seed of two fasciated 
specimens which had accidentally appeared the year be- 
fore. The normal were weeded out and the abnormal 
saved and allowed to set seed with a view to putting a 
new r variety on the market. 
In cases such as this, selection has a twofold object. 
In the first place the variety must be isolated, that is 
purged of the impurities resulting from free crossing. 
It must also be actually improved by selection. The first 
indications of doubling are, as we have seen, single super- 
numerary petals, or in composites single supernumerary 
ray florets on the disc ; the first indication of a new color 
is often very pale : slit leaves and petals are indicated by 
quite small imaginations, combs (Vol. I, p. 191) appear 
as small outgrowths. All these qualities had to be im- 
proved by selection up to the level of the mean of the 
character and then even perhaps beyond. 
An improvement of this kind, when once started, is 
effected not only rapidly but with increasing swiftness. 
DARWIN, he. cit., TT, p. 269. 
