Origin of Species Variorum

→ 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

→ irregular. 1859 1860 1861

irregular, nor that it goes on continuously; it is far more probable that each form remains for long periods unaltered, and then again undergoes modification. 1866 1869 1872

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~~

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,

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 the process ever goes on so regularly as is represented

in,

the diagram, though in itself made somewhat →irregular.