118 Atai'isjn. 
science of variability and mutability, and especially in that 
of atavism of which they perhaps afford the most beauti- 
ful examples. As such they have been dealt with espe- 
cially by Louis VILMORIN whose theory we will now pro- 
ceed to examine. 1 
VILMORIN starts from the observation that striped 
flowers only occur on those species which are themselves 
colored, but which also possess a white variety; or if the 
color of the flower is composed of red and yellow the 
uniform yellow variety may behave like the white (Mira- 
bil'iSf Antirrhinum). The first variety to arise is the 
white (or yellow) from which later on the striped form 
originates and VILMORIN explains this as a partial re- 
version to the parent species. 
White varieties of a large number of decorative plants 
have arisen in cultivation, and in fact many favorite ones 
in M. VILMORIN'S own nurseries. They can usually be 
easily "fixed" in the course of a few years ; that is to 
say, they are generally constant from the very beginning 
but have to be purged of the consequences of unavoidable 
crosses, and this takes a few years, as a rule. The striped 
sorts do not appear in this period, the hybrids resulting 
from the crosses are like the parent species and segregate 
into this and the pure white variety. The striping is not 
the result of crossing therefore ; moreover in such cases 
deliberate crossing has only resulted in the production 
of self-colored and not of variegated flowers. Also, 
when such hybrids exhibit sectorial variation, the color 
is in large patches and not in fine stripes. 
It is not until the white varieties have attained com- 
plete purity and have proved constant for a considerable 
1 Societe Pliilomatiqiic dc Paris, Seance du 17 Janvier, 1852, Pro- 
ccs-verbaux, p. 9; Notices sur I' amelioration des plantes par le semis, 
1886, p. 39; and B. VERLOT, Sur la fixation des varietes, 1865, pp. 62-66. 
