Oxalis rosea, long-styled form (Hildebrand) : 83.
Oxalis compressa, short-styled form : 83.
Pontederia (sp.?) short-styled form : 87.
Pontederia other sp. mid-styled form : 86.
We here see that, with seven or eight exceptions out of the forty-three cases,
the pollen-grains from one form are larger than those from the other form of the
same species. The extreme difference is as 100 to 55; and we should bear in mind
that in the case of spheres differing to this degree in diameter, their contents
differ in the ratio of six to one. With all the species in which the grains
differ in diameter, there is no exception to the rule that those from the
anthers of the short-styled form, the tubes of which have to penetrate the
longer pistil of the long-styled form, are larger than the grains from the other
form. This curious relation led Delpino (as it formerly did me) to believe that
the larger size of the grains in the short-styled flowers is connected with the
greater supply of matter needed for the development of their longer tubes. (6/2.
'Sull' Opera, la Distribuzione dei Sessi nelle Piante' etc 1867 page 17.) But
the case of Linum, in which the grains of the two forms are of equal size,
whilst the pistil of the one is about twice as long as that of the other, made
me from the first feel very doubtful with respect to this view.
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