BUD VARIATION. 
251 
all of previous hybridisation or crossing ; or, even where such 
has existed, the form produced is not like that of either of the 
supposed progenitors. 
Such cases as the fern-leaved beech do not seem explicable 
by either hypothesis. The sugar-cane, which rarely if ever 
flowers, and hence offers no opportunity for hybridisation, 
nevertheless produces new varieties by means of bud variation. 
Potato tubers, again, vary greatly often on the same plant, but 
these may be the result of former crossing. A case related by 
Mr. Meehan, in the sweet potato ( Convolvulus Batatas ), is, 
however, not open to this objection. The plant in question, it 
appears, never flowers in the Northern States of America, and 
yet it has been known to produce tubers of two distinct va- 
rieties — the 66 Red Bermuda ” and the u White Brazilian ” — on 
the same root. 
Reversion to an ancestral condition is a still more hypo- 
thetical cause than dissociation of mixed characters, as we have 
scarcely ever any means of knowing what the assumed con- 
dition was. We have, therefore, to look to other causes. We 
shall not advance matters much by attributing the changes 
in question to an innate tendency to vary possessed by buds 
as well as by seedling plants, which are, in so many respects, 
analogous with buds. Doubtless there is such a tendency, but 
we want to get at the “ why and wherefore ” of the proclivity. 
The following illustrations may in some slight degree furnish 
a clue to the attainment of the desired end. In the first place 
we must not overlook the circumstance that, under ordinary 
conditions, the several organs of plants often vary according to 
the part of the plant upon which they grow. Botanists recog- 
nise this when they give different names to the root-leaves, 
stem-leaves, floral-leaves, bracts, &c. Again, there are such 
cases as the seedless barberry. This plant can be propagated 
by cuttings, and its seedless condition can be thus perpetuated ; 
but if the plant be multiplied by suckers or shoots thrown up 
from the underground stem, the fruits produced have seeds as 
usual. This is an evidence of a difference in the internal 
organisation of different parts of the same plant. Another 
illustration of a similar character lately came under obser- 
vation, in which a sucker from the root of the tree of heaven, 
Ailanthus glandulosa , produced egg-shaped leaves and a dense 
cluster of flowers while only a foot or so in height (see fig. 1), 
the ordinary habit of the tree being to grow for several years 
before flowering, to form a lofty stem, and to produce large 
compound pinnate leaves like those of the common ash. This, 
in gardening phrase, would be a “ sport,” but it is clear it had 
nothing to do with hybridisation, the form produced being 
unlike that of any other allied plant. Moreover, there is no 
