UNISEXUALITY. L95 
Berol.,’ ii, p. 259. Tausch, ‘ Bot. Zeit.,’ 1833, i, p. 229. Koch, ‘ Synops. 
Flor. Germ.,’ 740. Host, ‘Flor. Aust.,’ ii, p. 641 (8. mirabilis). See 
also Hegelmaier, ‘Wiirttemberg Naturwissenschaft Jahreshefte,’ 1866, 
p. 30. Other references to less accessible works are given in ‘ Linnea,’ 
xiv, p. 372. 
Change from hermaphroditism to unisexuality.— Many 
flowers ordinarily hermaphrodite as to structure, be- 
come unisexual by the abortion or suppression of 
their stamens, or of their carpels, as the case may be. 
This phenomenon is lessened in interest since the 
demonstration of the fact by Darwin and others, that 
many plants, structurally hermaphrodite, require for the 
full and perfect performance of their functions the co- 
operation of the stamens and pistils, belonging to dif- 
ferent individuals of the same species. 
Some of the Ranunculacew constantly exhibit a ten- 
dency towards the dicecious condition, and the rarity 
with which perfect seeds of Ranunculus Ficaria are 
formed is to be attributed, in great measure, to the 
deficiency of pollen in the anthers of these flowers. 
Ranunculus auricomus also is frequently sterile. Speci- 
mens of Ranunculus bulbosus may be met with in which 
every flower is furnished with carpels, most of which 
have evidently been fertilised, although there are no 
perfect stamens in the flowers. 
Knight and other vegetable physiologists have been 
of opinion that a high temperature favours the pro- 
duction of stamens, while a lower degree of heat is 
considered more favorable to the production of pistils, 
and in this way the occurrence of ‘‘blind”’ strawberries 
has been accounted for. Mr. R. Thompson, writing 
on this subject, speaks of a plantation of Hautbois 
strawberries which in one season were wholly sterile, 
and accounts for the circumstance as follows: 
the plants were taken from the bearing beds the 
year previous, and were planted in a rich well-manured 
border, in which they started rapidly into too great 
luxuriance, the growth being to leaves rather than to 
fruit. The following season these same plants bore 
