SPECIES.—VARIETIES OR SUB-SPECIES. 401 
resemble any other plants, and which, taking Flowering Plants 
as illustrations, can be reproduced by seed; so that we may 
from analogy infer that they have all been derived originally 
from one common stock. Thus, if we walk into a field of Beans, 
Peas, or Clover, we observe thousands of individuals, which, al- 
though differing to a certain extent in size, and in some other 
unimportant characters, we at once associate together under a 
common name. In like manner we commonly observe around 
us, in the gardens and fields, similar collections of individuals. 
Such collections of plants, thus seen to resemble one another 
in all their important parts, constitute our first idea of a species ; 
and that idea is at once confirmed if, by taking the seeds of such 
plants and sowing them, we obtain other plants exactly resem- 
bling those from which such seeds have been derived. Species 
are, however, under special conditions, liable to variations, and 
we have then formed what are termed varieties and races. 
a. Varieties or Sub-species.—It has just been observed, that 
if the seed of a species be sown, it will reproduce its parent, or, 
in other words, produce a plant resembling its parent in all its 
important parts. But this will only happen, when the new in- 
dividual has been exposed to similar influences of soil, heat, 
light, moisture, and other conditions, as its parent ; and hence 
we tind that variations in such particulars will lead to certain 
peculiarities in form, colour, size, and other minor characters, 
in plants raised from the seeds of the same species. In this 
manner we have produced what are termed varieties. In some 
cases such variations are merely transient, and the individuals 
presenting such peculiarities will in time return to their original 
specific type, or perish altogether ; while in other instances they 
are permanent and continue throughout the life of the indi- 
vidual, the whole plant being, as it were, impregnated with 
the particular variations thus impressed upon it, and hence 
such variations may be perpetuated by the gardener in the 
operations of Budding, Grafting, &c. (see page 107), as is the 
case with many of our fruit trees and flowers. But even these 
varieties cannot be propagated by seed ; for if their seeds be 
sown, the individuals which will be produced will have a 
tendency to revert to the original species from which such 
varieties have been obtained, so that the nature of the plant 
raised will depend upon the character of the soil in which it is 
placed, and the other external conditions to which it is exposed. 
Thus, if we sow the seeds of a number of different varieties of 
Apples, the fruit subsequently produced by the new generation 
of Apple trees will, instead of resembling that of their parents, 
have a tendency to revert to that of the common Crab, from 
which species all such varieties have been originally derived. 
Hence a variety differs essentially from a species in the fact 
that it cannot be propagated by seed. 
b. Races.—-Besides the varieties just alluded to there are 
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