y often be perpetuated by
seed, yet they rarely produce seed in such abundance, or so prolific in
quality, as wild individuals; so that if the care of man were withdrawn,
the most fertile variety would always, in the end, prevail over the more
sterile.

Similar remarks may be applied to the double flowers, which present
such strange anomalies to the botanist. The ovarium, in such cases, is
frequently abortive; and the seeds, when prolific, are generally much
fewer than where the flowers are single.

_Changes caused by soil._--Some curious experiments, recently made on
the production of blue instead of red flowers in the _Hydrangea
hortensis_, illustrate the immediate effect of certain soils on the
colors of the calyx and petals. In garden-mould or compost, the flowers
are invariably red; in some kinds of bog-earth they are blue; and the
same change is always produced by a particular sort of yellow loam.

_Varieties of the primrose._--Linnaeus was of opinion that the primrose,
oxlip, cowslip, and polyanthus, were only varieties of the same species.
The majority of the modern botanists, on the contrary, consider them to
be distinct, although some conceived that the oxlip might be a cross
between the cowslip and the primrose. Mr. Herbert has lately recorded
the following experiment:--"I raised from the natural seed of one umbel
of a highly manured red cowslip a primrose, a cowslip, oxlips of the
usual and other colors, a black polyanthus, a hose-in-hose cowslip, and
a natural primrose bearing its flower on a polyanthus stalk. From the
seed of that very hose-in-hose cowslip I have since raised a
hose-in-hose primrose. I therefore consider all these to be only local
varieties, depending upon soil and situation."[814] Professor Henslow,
of Cambridge, has since confirmed this experiment of Mr. Herbert; so
that we have an example, not only of the remarkable varieties which the
florist can obtain from a common stock, but of the distinctness of
analogous races found in a wild state.[815]

On what particular ingredient, or quality in the earth, these changes
depend, has not yet been ascertained.[816] But gardeners are well aware
that particular plants, when placed under the influence of certain
circumstances, are changed in various ways, according to the species;
and as often as the experiments are repeated, similar results are
obtained. The nature of these results, however, depends upon the
species, and they are, therefore, p