THE THREE FORMS OF LYTHRUM SALICARIA. 187 
the eighteen possible unions the pollen-tubes penetrated, after 
eighteen hours, the stigma. I have reason to believe that the 
offspring from the illegitimate unions present some singular 
characteristics; but until my observations on this head are re- 
peated, I must be silent. At first I thought that perhaps two 
kinds of pollen placed together on the same stigma would give 
more fertility than any one kind; but we have seen that this is 
not the case with each form’s own two kinds of pollen; nor is it 
probable in any case, as I occasionally got, by the use of single 
kinds of pollen, fully as many seed as I have seen in a capsule 
naturally fertilized. Moreover the proper pollen from a single 
anther is more than sufficient to fully fertilize each stigma; hence, 
in this as in so many other cases, at least twelve times as much 
of each kind of pollen is produced as is necessary to ensure full 
fertilization. From the dusted condition of the whole body of 
those bees which I caught on these flowers, it is probable that 
some pollen of all kinds is deposited on each stigma; but there 
can hardly be a doubt that the pollen of the stamens of corre- 
sponding length will be prepotent and will wholly obliterate any 
effect from the other kinds of pollen, even if previously deposited 
on the stigma. I infer this partly from the fact ascertained by 
Giirtner that each species’ own pollen is so prepotent over that of 
any other species, that if put on the stigma many hours subse- 
quently, it will entirely obliterate the action of the foreign pollen. 
But I draw the above inference especially from the following 
experiment: I fertilized homomorphically or illegitimately some 
long-styled Cowslip flowers (Primula veris) with their own pollen, 
and exactly twenty-four hours subsequently I fertilized these 
same stigmas heteromorphically or legitimately with pollen from 
a short-styled dark-red Polyanthus. I must premise that I have 
raised many seedlings from crossed Cowslips and Polyanthus, and 
know their peculiar appearance ; and I further know, by the test 
of the fertility of the mongrels infer se, and with both parent 
forms, that the Polyanthus is a variety of the Cowslip, and not of 
the Primrose (P. vulgaris) as some authors have supposed. Now 
from the long-styled Cowslip twice fertilized in the manner ex- 
plained, I raised twenty-nine seedlings, and every one of them 
had flowers coloured more or less red; so that the heteromorphic 
Polyanthus-pollen wholly obliterated the influence of the homo- 
morphie pure Cowslip-pollen, which had been placed on the 
stigmas twenty-four hours previously, and not a single pure 
Cowslip was produced. 
