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nature lias doomed the variety to ultimate extinction, we see no reason' 
why plants raised from its seeds should escape the general contamination. 
A deteriorated plant produces deteriorated seed, and vice versa; and this- 
law applies as well to species as varieties. If the hypothesis be well- 
founded, there is no reason why plants produced from seed-tubers should 
feel the effects of degeneracy sooner than those produced from seed-balls. 
The potato propagates itself as naturally by tubers as by seed; and na¬ 
ture never fails to take the right direction in her generative economy. 
We have spoken of the two methods of propagation which nature has 
assigned to the vegetable kingdom; the oviparous as by seeds, and the 
viviparous as by buds and bulbs. By carefully examining the difference 
between these two methods, we shall see what is meant by the word 
‘extension’ as applied to viviparous propagation. Properly speaking, 
each bud is a separate individual plant. If cut from the branch, or stem, 
to which it belongs, and placed in the earth with a glass vessel inverted 
over it, so that its exhalation shall not exceed its power of absorption, it 
will throw down its roots and become an independent plant. If the same 
bud, however, were left to grow on the parent stem, instead of putting 
forth roots at its axillary point, it would send down its nutritive sap, 
elaborated for that purpose to the old roots, causing them to increase in 
size and give out new fibres, or rootlets, to supply the wants of the pa¬ 
rent tree, with its increasing family of branches. Thus, the thousands 
of buds which spring forth every year from the branches of a tree, are 
only so many separate plants whose roots constitute the bark and annual 
accumulations of the old tree. The plants of each year envelope with 
their descending sap, or material elaborated for their roots, those of the 
next preceding year, and so on, till the whole becomes a series of con¬ 
centric trees, of which the tree of the last year’s growth is always the 
most vigorous and hardy of the group. The central tree, or internal 
wood, ceases, in process of time, to perform its vital functions, and, de¬ 
caying, ultimately involves the whole structural system in a common 
ruin. Grafting, then, is only detaching the last tree from the family 
group and placing it upon a vigorous root; a process by which the indi¬ 
vidual series may be indefinitely extended. It is not an extension of the 
old tree, but a new offspring transferred from its native to a foreign stock; 
not a prolongation of life, but a renewal of it. Each new crop of buds 
