SELF-FERTILIZATION OF PLANTS, e 365 
Like that plant, the corolla of four minute petals is sometimes wanting. The stamens 
are reduced to four (opposite the sepals). The stigma is capitate, and it seeds very freely. 
So many genera have some one or more species with conspicuous flowers, and one or 
more other species which have them inconspicuous and self-fertilizing, that it is, I 
think, at least suggestive of the possibility of the latter having differentiated from the 
former by becoming self-fertilizing. A few out of many that might be mentioned will 
remind the reader of this fact. Cardamine hirsuta is small-flowered and highly self- 
fertile; but C. pratensis is larger-flowered, brightly coloured, and often barren. Stellaria 
Holostea is very conspicuous and proterandrous, but Stellaria media is profusely self- 
fertile. Malva sylvestris is highly conspicuous and proterandrous; but M. rotundifolia 
is inconspicuous and self-fertile. Lastly, large-flowered Geraniums are proterandrous, 
but smaller-flowered species are mostly or entirely self-fertile. 
Such cases might be multiplied almost indefinitely ; and I shall have occasion to allude 
to them again hereafter. The general conclusion I would draw is that the self-fertilizing 
species are derived from certain intercrossing forms (many of which may be now alto- 
gether extinct) by adaptation to self-fertilization, the probable cause of this being the 
neglect of insects to visit them. 
SAXIFRAGACEJE.— The species of Saxifraga are mostly more or less conspicuous, honey- 
bearing, and proterandrous; but Chrysosplenium has insignificant flowers, and the 
anthers and stigma mature together. Müller observes of C. alternifolium that, although 
itis thus adapted for self-fertilization, yet the general golden aspect of the clusters of 
flowers and leaves render it more or less attractive to insects. 
Drosera rotundifolia has cleistogamous flowers, while with D. anglica * the still folded 
petals on some plants in my greenhouse opened just sufficiently to leave a minute 
aperture; the anthers dehisced properly, but the pollen-grains adhered in a mass to 
them, and thence emitted their tubes, which penetrated the stigmas. These flowers, 
therefore, were in an intermediate condition, and could not be called either perfect or 
cleistogamie " (* Forms of Flowers,’ p. 329). 
UMBELLIFERÆ.—Of this extensive Order, the majority, with conspicuous umbels of 
flowers, are much visited by insects, are highly mellifluous, and for the most part pro- 
terandrous, "There are, however, some very insignificant forms, which one may suspect 
would prove self-fertilizing, but I have not had an opportunity of examining them, such 
as Bupleurum &c.; but Scandix Pecten-Veneris, with its minute flowers and very small 
umbels, is certainly self-fertilizing. The umbel consists of about five or six flowers only. 
The stamens remain incurved when dehiscing. There are two or three male flowers in 
the centre, the anthers of which burst later, so that it would appear that if the herma- 
phrodite flowers do not fertilize themselves, they can be pollinated by the subsequent 
male flowers. The retention of the incurved position of the stamens shows clearly that 
this method of self-fertilization, and which is particularly common, as in Potentilla 
Fragariastrum, is usually nothing more than the position of the stamens when in the 
bud retained after the corolla has expanded, though in Agrimonia and Alisma im 
are subsequently incurved. 
. SECOND SERIES.— BOTANY, TOL. I. 3E 
