cotiana major vulgaris; (2)
perennis; (3) Transylvanica; (4) a sub-var. of the last; (5) major latifol.
fl. alb.

[237] Koelreuter was so much struck with this fact that he suspected that a
little pollen of _N. glutinosa_ in one of his experiments might have
accidentally got mingled with that of _var. perennis_, and thus aided its
fertilising power. But we now know conclusively from Gaertner
('Bastarderz.,' s. 34, 431) that two kinds of pollen never act _conjointly_
on a third species; still less will the pollen of a distinct species,
mingled with a plant's own pollen, if the latter be present in sufficient
quantity, have any effect. The sole effect of mingling two kinds of pollen
is to produce in the same capsule seeds which yield plants, some taking
after the one and some after the other parent.

[238] Mr. Scott has made some observations on the absolute sterility of a
purple and white primrose (_Primula vulgaris_) when fertilised by pollen
from the primrose ('Journal of Proc. of Linn. Soc.,' vol. viii., 1864, p.
98); but these observations require confirmation. I raised a number of
purple-flowered long-styled seedlings from seed kindly sent me by Mr.
Scott, and, though they were all some degree sterile, they were much more
fertile with pollen taken from the common primrose than with their own
pollen. Mr. Scott has likewise described a red equal-styled cowslip (_P.
veris_, idem, p. 106), which was found by him to be highly sterile when
crossed with the common cowslip; but this was not the case with several
equal-styled red seedlings raised by me from his plant. This variety of the
cowslip presents the remarkable peculiarity of combining male organs in
every respect like those of the short-styled form, with female organs
resembling in function and partly in structure those of the long-styled
form; so that we have the singular anomaly of the two forms combined in the
same flower. Hence it is not surprising that these flowers should be
spontaneously self-infertile in a high degree.

[239] 'Act. Acad. St. Petersburg,' 1780, part ii., pp. 84, 100.

[240] 'Annales des Sc. Nat.,' tom. xxi. (1st series), p. 61.

[241] 'Bull. Bot. Soc. de France,' Dec. 27th, 1861, tom. viii. p. 612.

[242] Quoted by Isid. Geoffroy St. Hilaire, 'Hist. Naturelle Generale,'
tom. iii. p. 476. Since this MS. has been sent to press a full discussion
on the present subject has appeared in Mr. Herbert Spencer's 'Principles of
Biology,' vol. ii. 1