APPENDIX. 4YY 
tive action is stopped, at least partially—pretty much as it would be if 
the plant were placed in the opposite condition of starvation. The 
effect of supplying a plant (or an animal) with an excessive supply of 
food, which it cannot assimilate,is in many respects similar to that 
which results from partially cutting off the supplies. And the same 
reasoning applies to sterility. If by high culture, or the supply of an 
undue quantity of nourishment, the constitution of the plant be im- 
paired, or if the plant be pampered, it is mo wonderful thing that sterility 
shouldensue. Hence, then, may it not be asserted as a general principle 
that in the production of double flowers a partial arrest of development, if 
not of growth, however produced, is an essential preliminary ? All the 
attendant phenomena, such as the obliteration of the stamens, the 
augmentation in the number of floral whorls, the occurrence of prolifi- 
cation, are consistent with the supposition of a primary arrest of 
development, more or less complete, as the case may be: at one time 
permanent, at another time relaxed and intermittent, or in a third set 
of cases the vegetative activity or power of growth may be restored, and 
from the centre of the flower may spring a perfect branch with perfect 
leaves, the production of sheaths only being superseded by the develop- 
ment of leaves, in which all the parts—sheath, stalk, and biade—are 
present. 
When once the disposition to form double flowers is established, that 
tendency becomes hereditary ; there are races of single Stocks in which, 
out of hundreds of plants, scarcely one double-flowered form is met 
with ; but when the tendency to produce double blooms is set up, single 
flowers become the exception: thus, in the Balsams, before mentioned, 
not one in fifty now produces single flowers, and the seeds of these 
double Balsams produce double-flowered seedlings, with scarcely a 
“rogue” among them. 
The following list of plants producing double flowers of any kind 
is taken from that given in ‘ Seemann’s Journal of Botany,’ vol. ii, p. 177, 
and to which some additions have been made. Miscalled double flowers, 
such as those of the Composite, Viburnum Hydrangea, &c., are excluded. 
RANUNCULACEZ. 
Clematis Viticella, Linn., 8. Europe. 
florida, Thunb., Japan. 
Fortunei, Moore, Japan. 
patens, Desne, Japan. 
Anemone japonica, Sieb. et Zuce., Japan. 
coronaria, Linn., S. Europe, Asia Minor. 
hortensis, var. Linn., S. Hurope. 
palmata, Linn., N. Africa, Spain, Portugal. ‘ 
nemorosa, Linn., Europe, N. America, Siberia. 
sylvestris, Linn., S. Europe, Siberia. 
