On the Species of the Genus Primula in Essex. 157
III.—The Relative Numbers of the Two Forms in Nature.
Mr. Darwin has stated14 that "the two forms exist in a
wild state in about equal numbers"; but, from my observa-
tions, I shall, I think, be able to prove that this is not the
case—there being a considerably larger number of long-styled
plants than of short-styled ones. The above statement is
made whilst treating of the Cowslip, but I presume that it
may be taken to refer also to the other species of Primula.
It is a little curious (although I regard it as a mere coin-
cidence) that all the particulars on this point actually given
by Darwin point to a conclusion differing from the results of
my own observations; but as I have counted far more plants
than he, and as this is a matter of fact and not of opinion, I
venture to claim an ability to prove my case. For instance,
he says of the Cowslip,15 "I collected 522 umbels from plants
growing in several stations, taking a single umbel from each
plant; and 241 were long-styled and 281 short-styled," or as
86 to 100. Of the Primrose he says,16 "Mr. Scott examined
100 plants growing near Edinburgh, and found 44 to be long-
styled and 56 short-styled; I took by chance 79 plants in
Kent, of which 39 were long-styled and 40 short-styled; so
that the two lots together consisted of 83 long-styled and 96
short-styled," or as 86 to 100. He also quotes an authority17
who counted 29 hybrid Oxlips in Surrey, of which 13 were
long-styled and 16 short-styled, or as 81 to 100. My own
observations here follow in detail. My plan of operations
was very simple : I merely gathered a single flower or a
single umbel from each plant, and afterwards counted them.
different heights; and I noticed more than one umbel on which there
were both ordinary flowers and other flowers which were normal in every
respect, except that the stigma was not raised more than one-eighth of an
inch above the ovary. This great variability in the length of style seems
to indicate that the plant is a little inclined towards heterostylism.
[Muller also states (' Die Befruchtung der Blumen') that P. longiflora is
homostylic, and adapted by its long narrow corolla-tube for fertilization
by Lepidoptera. The tube is 16 to 24 mm. long, and the nectar is, there-
fore, accessible only to Macroglossa stellatarum (with proboscis 25 to 28
mm. long), and to Deilephila euporbiae (25 mm.) among all the Alpine
Lepidoptera.—Ed.]
14 'Forms of Flowers,' p. 18. 15 Ibid., p. 18. 16 Ibid., p. 31. 17Ibid., p. 70.