76 MR. DARWIN ON THE EXISTENCE OF TWO FORMS 
soon, I did not transplant them, and they unfortunately grew with 
their branches closely interlocked. All the plants were covered 
by a net, excepting one of each form. First, of the long-styled 
flowers, twelve were homomorphically fertilized by their own-form 
pollen, taken in every case from a separate plant; and not one 
flower set a seed-capsule: twelve other flowers were heteromor- 
phically fertilized by pollen from short-styled flowers ; and they set 
nine pods, each including on an average seven good seeds: as 
before, ten seeds is the maximum possible production. Secondly, 
of the short-styled flowers, twelve were homomorphically fertilized 
by own-form pollen, and they yielded one capsule, including only 
three good seeds; twelve other flowers were heteromorphically 
fertilized by pollen of long-styled flowers, and these produced nine 
capsules, but one was bad; the eight good capsules contained on 
an average exactly eight good seeds each. 
The many flowers on the eleven long-styled plants under the 
net, which were not fertilized, produced only three capsules 
(including 8, 4, and 1 good seeds) ; whether, owing to the inter- 
locking of the branches, these accidentally received pollen from 
the other form, I will not pretend to conjecture. The single long- 
styled plant which was uncovered, and grew close by the uncovered 
short-styled plant, produced five good pods ; but it was avery poor 
and small plant. 
The flowers borne on the thirteen short-styled plants under the 
net, which were not fertilized, produced twelve capsules (containing 
56 seeds on average) : as some of these capsules were very fine, and 
five were borne on one twig, I suspect that they had been visited 
by some minute insect which had accidentally got under the net 
and had carried pollen from the other form. The one uncovered 
short-styled plant yielded exactly the same number of capsules, 
namely, twelve. 
From these facts we have some evidence, as in the case of L. 
grandiflorum, that the short-styled plants are in a very slight 
degree more fertile with their own pollen than are the long-styled 
plants. And we have the clearest evidence, from the result of the 
forty-eight flowers artificially fertilized, that the stigmas of each 
form require pollen from the stamens of corresponding height 
produced by the opposite form. 
In contrast with the case of L. grandiflorum, it is a singular fact 
that the pollen-grains of both forms of L. perenne when placed on 
their own-form stigmas, though not causing fertility, yet emit their 
tubes; and these tubes I found, after an interval of eighteen 
