358 REV. GEORGE HENSLOW ON THE 
G, pyrenaicum; which, again, are much larger than those of G. malle, while those of G. pusillum are 
still'smaller. These differences of size appear to be connected with other remarkable differences between 
the species. In G. pratense five of the stamens raise themselves and stand upright, and surround the 
still immature pistil. ` When they have shed their pollen they sink back and shrivel up, when the other 
five raise themselves. At a later stage these in their turn fall back and shrivel up; but the stigma does 
not become mature until all the stamens have shed their pollen. Under these circumstances G. pratense 
has lost the power of self-fertilisation, and is absolutely dependent on the visits of insects. G. pyrenaicum 
is also proterandrous; but while in G. pratense the pistil is not mature until the stamens have shed 
all their pollen and fallen back, in G. pyrenaicum the second series of stamens are still upright when ` 
the stigmatic lobes unfurl; the flower is consequently less absolutely dependent on insects, and we see ` 
that the corolla is much smaller. In the third species, G. molle, the pistil matures before the second 
series of stamens, and the corolla is still smaller; while in G. pusillum the pistil matures before any of 
the stamens.” Thus, then, these four species may be arranged in atable (slightly modified) as below :—- 
G. pratense. G. pyrenaicum, ; G. molle. G. pusillum. 
Flower large. Flower small. ; Flower smaller. S Flower smallest, 
First exclusively male, | First exclusively male, | First exclusively male, | First exclusively female, 
then exclusively female. then homogamous*. then homogamous. very soon homogamous. 
Incapable of self-fertiliza- | Generally fertilized by Often self-fertilized. Probably entirely self- | 
tion. | inseets. fertilized. 
I have quoted this passage, for it both entirely corroborates and so well expresses 
what I have myself observed, both in regard to Geranium as of many other genera ; and | 
it illustrates what I believe to be the origin of a large number of * species’ of plants, 
namely, the change from a state requiring intercrossing to self-fertilizing conditions. 
1t would be rash to assert that the above four species represent actual linear descendants, 
but they doubtless typify stages of descent from forms like @. pratense to G.. pusillum. 
The description of G. pusillum as being * at first exclusively female,” the reader will 
see, is exactly paralleled by several cases already mentioned, as of the Cruciferze, and will 
be again illustrated by following ones, and e ae P the origin of Proterogynous 
flowers generally. 
G. Robertianum. In this very common species I have found specimens growing in à 
wood, and not likely to be visited by insects, with the pollen-grains caught by the  — 
stigmas in the unopened buds, and self-fertilization apparently being secured. In some 
flowers the anthers of the lower stamens were spread out and the stigmas likewise; the ` 
latter also were curling backwards oe the anthers, : much in the same way as ‘occurs : 
in small-flowered Mallows. 
Erodium cicutarium. Though sometimes proterandrons, this can completely ‘fertilize | 
itself. The loss of five stamens in this eed is probably correlated with this rever- 
sion to complete self-fertility. 
Pelargonium. Ihave given figures opa XLIV. figs. 11 a, b) to show the strongly. 
ZS Sir J. Lubbock used the wad “ hermaphrodite,” for which I have substituted “ homogamons.” The former 
“merely means that stamens and min are in the same flower; the latter that, in E to this, ee V 
ean be dioi, | ; 
