e adds that in some seasons certain varieties
of this plant all prove good, and the next season all prove bad; whilst
exactly the reverse happens with other varieties. In 1845 the editor of
the 'Gardener's Chronicle'[661] remarked how singular it was that this
year many Calceolarias tended to assume a tubular form. With
Heartsease[662] the blotched sorts do not acquire their proper
character until hot weather sets in; whilst other varieties lose their
beautiful marks as soon as this occurs.

Analogous facts have been observed with leaves: Mr. Beaton asserts[663]
that he raised at Shrubland, during six years, twenty thousand
seedlings from the Punch Pelargonium, and not one had variegated
leaves; but at Surbiton, in Surrey, one-third, or even a greater
proportion, of the seedlings from this same variety were more or less
variegated. The soil of another district in Surrey has a strong
tendency to cause variegation, as appears from information given me by
Sir F. Pollock. Verlot[664] states that the variegated strawberry
retains its character as long as grown in a dryish soil, but soon loses
it when planted in fresh and humid soil. Mr. Salter, who is well known
for his success in cultivating variegated plants, informs me that rows
of strawberries were planted in his garden in 1859, in the usual way;
and at various distances in one row, several plants simultaneously
became variegated, and what made the case more extraordinary, all were
variegated in precisely the same manner. These plants were removed, but
during the three succeeding years other plants in the same row became
variegated, and in no instance were the plants in any adjoining row
affected.

The chemical qualities, odours, and tissues of plants are often
modified by a change which seems to us slight. The Hemlock is said not
to yield conicine in Scotland. The root of the _Aconitum napellus_
becomes innocuous in frigid climates. The medicinal properties of the
Digitalis are easily affected by culture. The Rhubarb flourishes in
England, but does not produce the medicinal substance which makes the
plant so valuable in Chinese Tartary. As the _Pistacia lentiscus_ grows
abundantly in the South of France, the climate must suit it, but it
yields no mastic. The _Laurus sassafras_ in Europe loses the odour
proper to it in North America.