That the lessened size of the corolla in the above case is in some
manner an indirect result of the modification of the reproductive organs is
supported by the fact that in Rhamnus catharticus not only the petals but the
green and inconspicuous sepals of the female have been reduced in size; and in
the strawberry the flowers are largest in the males, mid-sized in the
hermaphrodites, and smallest in the females. These latter cases,--the
variability in the size of the corolla in some of the above species, for
instance in the common thyme,--together with the fact that it never differs
greatly in size in the two forms--make me doubt much whether natural selection
has come into play;--that is whether, in accordance with H. Muller's belief, the
advantage derived from the polleniferous flowers being visited first by insects
has been sufficient to lead to a gradual reduction of the corolla of the female.
We should bear in mind that as the hermaphrodite is the normal form, its corolla
has probably retained its original size. (7/24. It does not appear to me that
Kerner's view 'Die Schutzmittel des Pollens' 1873 page 56, can be accepted in
the present cases, namely that the larger corolla in the hermaphrodites and
males serves to protect their pollen from rain. In the genus Thymus, for
instance, the aborted anthers of the female are much better protected than the
perfect ones of the hermaphrodite.
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