It has long been known from the researches of Kélreuter


and Gartner, that two species when crossed reciprocally


sometimes differ as widely as is possible in their fer-
tility : thus A when crossed with the pollen of B will
yield a large number of seeds, whilst B may be crossed
repeatedly with pollen of A, and will never yield a single
seed. Now Mr. Scott shows in several cases that the
same law holds good when two heterostyled species
of Primula are intercrossed, or when one is crossed
with a homostyled species. But the results are much
more complicated than with ordinary plants, as two
heterostyled dimorphic species can be intercrossed in
eight different ways. I will give one instance from
Mr. Scott. The long-styled P. hirsuta fertilised legi-
timately and illegitimately with pollen from the two
forms of P. auwricula, and reciprocally the long-styled
P. auricula fertilised legitimately and illegitimately
with pollen from the two forms of P. hirsuta, did
not produce a single seed. Nor did the short-
styled P. hirsuta when fertilised legitimately and
illegitimately with the pollen of the two forms of
P. auricula. On the other hand, the short-styled
P. auricula fertilised with pollen from the long-styled
P. hirsuta yielded capsules containing on an average
no less than 56 seeds; and the short-styled P.
auricula by pollen of the short-styled P. hirsuta


yielded capsules containing on an average 42 seeds


* ‘Journ, Linn, Soc. Bot.’ vol. viii. 1864, p. 93 to end.
