338 Nutrition and Selection. 
beds long before they exhibit buds. 1 The lower pods 
on the main stem and on the principal branches as well 
as the lower two-thirds of each pod furnish on the 
average more double than single plants; the upper sec- 
tions of the pod and the pods of weaker branches yield 
more single ones. The proportion of double plants in 
the harvest can be increased to about 60% either by lim- 
iting the production of seed by means of culture in pots, 
or by pruning; and in the best nurseries the finer sorts 
are usually subjected to this treatment. If the seeds 
are kept through some years the proportion of double 
seedlings gradually increases, because the mortality is 
greater amongst seeds that were destined to produce 
singles. 
It is stated that in the case of the Balsam and many 
other double flowered varieties the seeds are rounder 
and fuller and also smoother than those of the corre- 
sponding single sorts. The "double" seeds of Petunia 
are said to germinate later than the single ones, so at 
least I have been told by nursery men at Erfurt. In the 
Composites the central seeds of the disc in double vari- 
eties are said to be more likely to repeat the anomaly 
than the marginal ones. All these statements should, 
however, be regarded critically, and many of them are 
in need of experimental confirmation. 2 
Nevertheless the general rule is that the various seeds 
of a plant may give rise to offspring of widely different 
degrees of individual vigor, according to the place of 
their origin on the parent plant, their size and their 
1 This process which is carried out by children is called esimplcr, 
in France. The matter stands in need of closer investigation. 
2 PEYRITSCH has collected references to the earlier literature re- 
lating to this point. Zur Aetiologie pclorisclier Bliithcnbildnngcn, 
Abhandl. k. k. Akad. Wien, 1877, pp. 135-136. 
