THE PRINCIPLES OF BOTANY. 
329 
B. DEHISCENT PERICARPS. 
Examples—Pseony, pea, cabbage, poppy, bellflower. 
II. Fruits, multiple, or formed by the union of several - 
flowers: 
Examples—Fig^ fir-cones, pine-apple, bread-fruit. 
Our advanced forms of edible fruits may be viewed as 
being for the most part derivatives from far different and 
oftentimes flavourless or nauseous parents, thus—the apple 
from the wild crab, the plum from the common sloe; whilst 
probably peaches and nectarines are but advanced forms of 
some plums. 
Many of our cultivated fruits have no analogy either in 
this or any other country, and hence they may be concluded 
as the changed offspring by selection. When, however, a 
favourite fruit is attained, there is no difficulty in propa¬ 
gating it even upon trees of the opposite nature; thus^ by 
inserting a bud of the former into the latter, by budding, or 
by attaching a branch of the former to the latter; by grafting 
we perpetuate a favourite sort. Both budding and grafting 
are operations so well known that we need not in this place 
either describe the methods by which the operations may be 
performed, or the general physiology connected with the 
question. Still, a statement of some of the effects of the 
process may not be out of place, as indicating the true prin¬ 
ciples involved. 
By grafting,^^ says Balfour (and we may say budding 
also) all our good varieties of apples have been produced 
from the crab-apple.’^ The seeds of the cultivated apples 
when sown produce plants which have a tendency to revert 
to the original sour crab. Grafted varieties can only be 
propagated by cutting. The influence exercised by the stock 
is very marked, and it is of great importance to select good 
stocks on which to graft slips. In this way the fruit is often 
much improved by a process of ennobling as it is called. 
The scion also seems in some cases to exercise a remarkable 
effect on the stock. Slips taken from varieties with varie¬ 
gated leaves grafted on non-variegated have caused the leaves 
of the latter to assume variegation, and the effect when once 
established has continued even after the slip was removed. 
The effects of grafting are well seen in the case of the red 
laburnum when united to the yellow species. The red la¬ 
burnum is a hybrid between the common yellow laburnum 
and Cytisus pw'pureus, or the purple laburnum ; the branches 
