On the Species of the Genus Primula in Essex. 167
produced by each umbel is almost exactly identical with that
produced by the plant. It will be seen that the s. are the
most fertile in the proportion of 4 to 8. Of the s. flowers 14
bore no seed, but more than double as many of the 1., viz. 31,
were barren. The four highest numbers of seeds produced
by the s. are 97, 101, 104, and 106 ; and the four highest
numbers of seeds produced by the 1. are 70, 75, 76, and 90.
The former were all, however, on one plant, but their lowest
number is higher by 7 than the highest of the latter.23
P. viscosa.—At the end of August I gathered capsules from
plants growing in two places near St. Moritz. Many had
already shed their seed and a number of capsules burst, and
so were spoiled (particularly of the s.) before I counted
them. Table XV. shows that the two forms produce on an
average exactly the same number of flowers per umbel, but
that each flower of the s. produces 22 and the 1. 15 seeds ;
while the product of each umbel is almost exactly in the
same proportion. Of the s. capsules 14 produced no seed
against no less than 51 in the 1., or nearly 4 to 1. The four
highest numbers produced by the s. are 49, 49, 51, and 57 ;
and the four highest numbers produced by the 1. are 55, 55,
59, and 64. This is different from usual, as the highest
numbers are generally on the side of the s.24
P. latifolia.—I have counted a few (605) seeds belonging to
this species, but for some reason the flowers had never been
fully fertilized—no less than 75 per cent. producing 110 seed.
The s. produced 8 capsules an umbel to 7 in the 1.; the s. pro-
duced 52 seeds per umbel, the 1. 63; the s. produced 7 seeds
per capsule, the 1. 9, so that in this case, as with the
Cowslip, the most fertile flowers were the long-styled.
Probably it will be found (as Darwin says is the case with
P. sinensis) that the corolla in falling off (as it does with
this species and the last) drags the anthers over the stigma,
thus rendering the 1. most fertile; but I shall recur to this
subject.
23 [We learn from Muller's 'Die Befruchtung der Blumen' that Primula
farinosa occurs both on the Alps and in North Germany, and probably
owes this wide distribution to the mild climate succeeding the Glacial
period. On the Alps, where it is visited by Lepidoptera in great numbers
(Muller noted forty-eight species), the entrance of the flower is narrower
than in North Germany, where butterflies and moths are less plentiful,
and where the plant has probably to depend for cross-fertilization upon
the visits of bees.—Ed.]
24 The table is, however, seriously wanting in one particular. It does
not show the average number of umbels produced by each plant of each
form. This is because the plants of this species grow so thickly clustered
together on the rocks that I could not distinguish one from the other.