CHAP. IT. IRREGULAR METAMORPHOSIS. 
547 
sionally disappears, and the whole siibstance of the seed vessel 
consists of lax cellular tissue. In the orange a second fruit 
is sometimes produced in the inside, agreeing in all respects 
with the outer fruit, even in peel ; this is doubtless due to an 
attempt at producing a second series of pistilla. In a variety 
of the citron, called the fingered shaddock, well known in 
China, this tendency to form a second row of pistilla is not 
only in excess, but the cells of the fruit, in attempting to 
separate themselves into the simple individuals of which the 
fruit of the shaddock is ordinarily composed, divide it into 
distinct lobes irregularly arranged round a common axis. 
Having thus passed in review the irregular metamorphoses 
of plants through all the different parts, there still remains a 
subject on which it is requisite to say a few words. This is 
the permanency of such metamorphoses, or their capability of 
being perpetuated by seeds. It is a general law of nature, 
that seeds will perpetuate a species, but not a variety ; and 
this is no doubt true, if rightly considered : and yet it may 
be urged, if this be so, how have the varieties, w^ell known to 
gardeners and agriculturists, for many years been unceasingly 
carried on from generation to generation without change ? 
The long, red, and round white radishes of the markets, for 
instance, have been known from time immemorial in the same 
state in which they now exist. The answer is this. A species 
will perpetuate itself from seed for ever imder any circum- 
stances, and left to the simple aid of nature : but accidental 
varieties cannot be so perpetuated ; if suffered to become 
wild, they very soon revert to the form from which they 
originally sprung. It is necessary that they should be cul- 
tivated with the utmost care ; that seed should be saved from 
those individuals only in which the marks of the variety are 
most distinctly traced ; and all plants that indicate any dis- 
position to cast off their peculiar characteristics should be 
rejected. If this is carefully done, the existence of any 
variety of annual or perennial plant may undoubtedly be pro- 
longed through many generations; but in woody plants 
this scarcely happens, it being a rare occurrence to find 
any variety of tree or shrub producing its like when increased 
by seed. 
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