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generally to vary 1859 1860 1861 1866 1869
commonly 1872

their parents varied. 1859 1860 1861 1866 1869
did their parents. 1872

these circumstances we know to be 1859 1860 1861 1866 1869
all these circumstances are 1872

a 2 , 1859 1861 1866 1869 1872
a 2 , 1860

a 1 . 1859 1861 1866 1869 1872
a 1 . 1860

s 2 , 1859 1861 1869 1872
s 2 , 1860
8 2 , 1866

varieties will generally
still
continue to
be exposed to the same conditions which made their parents variable, and the tendency to variability is in itself
hereditary;
hereditary,
consequently they will
likewise tend
tend
to vary, and generally to vary in nearly the same manner as their parents varied. Moreover, these two varieties, being only slightly modified forms, will tend to inherit those advantages which made their
common
....
parent (A) more numerous than most of the other inhabitants of the same country; they will
like-wise
also
likewise
partake of those more general advantages which made the genus to which the parent-species belonged, a large genus in its own country. And these circumstances we know to be
favorable
favourable
to the production of new varieties.
If, then, these two varieties be variable, the most divergent of their variations will generally be preserved during the next thousand generations. And after this interval, variety a 1 is supposed in the diagram to have produced variety a 2 , which will, owing to the principle of divergence, differ more from (A) than did variety a 1 . Variety m 1 is supposed to have produced two varieties, namely m 2 and s 2 , differing from each other, and more considerably from their common parent (A). We may continue the process by similar steps for any length of time; some of the varieties, after each thousand generations, producing only a single variety, but in a more and more modified condition, some producing two or three varieties, and some failing to produce any. Thus the varieties or modified
descendants
descendants,
of
proceeding from
the common parent (A), will generally go on increasing in number and diverging in character. In the diagram the process is represented up to the ten-thousandth generation, and under a condensed and simplified form up to the fourteen-thousandth generation.
But I must here remark that I do not suppose that