Origin of Species Variorum

→ Crossed, 1866 1869

crossed, 1859

crossed , 1860 1861

Crossed , 1872

→ Offspring . 1866 1869

offspring .— 1859 1860 1861

Offspring , not universal . 1872

→ a most forcible 1859 1860 1861 1866

an overwhelming 1869 1872

→ and that there must be some error in all the foregoing remarks, 1859 1860 1861 1866

OMIT 1869 1872

→ the 1866 1869 1872

very generally the 1861

↑ 1 blocks not present in 1861 1866 1872; present in 1869 1859 1860

I fully admit that this is almost invariably the case.

→ the subject is surrounded by difficulties, for, looking 1866 1872

if we look 1859 1860

the subject is surrounded by difficulties, for looking 1861

→ OMIT 1861 1866 1872

we are immediately involved in hopeless difficulties; for 1859 1860

→ forms hitherto reputed to be 1861 1866 1872

hitherto reputed 1859 1860

→ OMIT 1866 1869 1872

the primrose and cowslip, 1859 1860 1861

→ most 1866 1869 1872

many of our best 1859 1860 1861

gained, in the case of dimorphic and trimorphic plants, at the expense of all the plants of the same form being rendered more or less sterile when united, and producing more or less sterile offspring. With respect to the steps by which it is probable that plants have been rendered dimorphic and trimorphic, want of space prevents my entering on the subject; but I will add that there is no special difficulty in this having been effected through variability, through the good gained by the prepotency of one sort of pollen over another, and through the accumulative action of natural selection.

Fertility

Varieties

when

→ Crossed,

and

their

Mongrel

→ Offspring .

It may be urged, as →a most forcible

argu- ment,

argument,

that there must be some essential distinction between species and varieties, →and that there must be some error in all the foregoing remarks, inasmuch as

the latter,

varieties,

however much they may differ from each other in external appearance, cross with perfect facility, and yield perfectly fertile offspring. With some exceptions, presently to be given, I fully admit that this is →the rule. ↑ But →the subject is surrounded by difficulties, for, looking to varieties produced under nature, →OMIT if two →forms hitherto reputed to be varieties be found in any degree sterile together, they are at once ranked by most naturalists as species. For instance, the blue and red pimpernel, →OMIT which are considered by →most botanists as varieties, are said by Gärtner

~~not~~

not

to be quite

sterile

fertile

when crossed, and he consequently ranks them as undoubted species. If we thus argue in a circle, the fertility of all varieties produced under nature will assuredly have to be granted.

If we turn to varieties, produced, or supposed to have been produced, under domestication, we are still

involved

in- volved