BUD VARIATION. 
247 
of contracted shoots so strikingly resembling birds’ nests. A 
similar occurrence is not uncommon in the wild cherry ; and a 
correspondent — Mr. Webster, of the gardens, Grordon Castle — 
informs us that he has observed similar growths in the common 
laburnum, in the Wych elm, and in the Scotch fir. Sometimes 
the determining cause may be discovered in the shape of an 
insect or fungus, but in this case the unusual condition ceases 
with the destruction of the impeding cause, whatever it may 
be, and the condition cannot then be perpetuated by the art of 
the gardener. 
Variation in the colour of certain leaves or flowers is an 
equally common occurrence, and is perhaps more easily under- 
stood. Each individual cell, to a large extent, lives inde- 
pendently of its neighbours, and the secretions it forms and 
deposits are very often different from those of adjoining cells*. 
Colouring materials, especially fluid ones, are notoriously liable^ 
to be formed in isolated cells. Again, variations in colour so* 
often depend on the mere superposition of cells containing 
material of different tints, that the changes met with, though 
striking to the eye, do not seem to indicate so complete a . 
change as in the case of alterations of form or size. Very many' 
of the variegated Pelargoniums, so fashionable now-a-days, have? 
originated as “ sports” from some previously existing variety. 
The intrinsic change between some of these varieties, even 
where apparently very considerable differences exist, is, in 
some instances, very slight. 
A marked difference in the amount and quality of the pubes- 
cence is not unfrequently manifested in some of these cases of 
bud variation. A plant which ordinarily has its leaves and its 
younger branches invested with a coating of hairs (epidermal 
appendages), all on a sudden produces a shoot on which the 
leaves are destitute of such clothing, or vice versa. Some of 
the moss roses have originated from plain-leaved varieties in 
the manner just indicated. 
But of all these cases the most striking are those which involve 
a change of form. We see, for instance, not unfrequently a 
particular branch bearing leaves very different from those on 
the rest of the tree, so different that but for their production 
on one and the same tree, the observer might readily take them 
to belong to different species. Many trees now cultivated for 
ornamental purposes have originated in this manner, such as 
the cut-leaved beech, the oak-leaved laburnum, and very many 
more, commonly to be found in plantations. Very often the 
whole u habit ” or aspect of the tree is altered by these varia- 
tions : thus many of the so-called “ weeping trees ” have sprung 
from a solitary branch of a tree which presented a pendulous 
character. Some trees, it may be remarked, naturally produce 
