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Sept. 24— 1861. (After considering Primula.)

The creationist who sees organisms from arctic & tropical countries or from 2 continents, which never could meet, sterile together, must admit this incidental from endowed sterility to present forms which do come into contact from blending — So with sterility of Hybrid progeny.—

Hence on view of sterility acquired by Nat Selection no difficulty from such facts.—

In animals hard to see why sterility shd have been acquired, why not mere instinctive dislike, which does prevail, why is sterility superadded.— If animal born with slightly different habits of life & at same time by chance some sterility concurred, it would be great advantage. In plants, where no instinctive choice such sterility necessary.—

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Perhaps cases of Birds which pair for life greatest difficulty, how cd. Nat. selection, come in? Yet it could if new var. paired with old it would be lost: if paired with similar var it would be preserved.— Sterility must supervene at first formation of var.— When we see how almost universal some sterility is, can we believe always acquired?

Must be incidental.— When whole body of a species changes like our Race-Horse, no use in sterility — if one body changed in England & another in America, such 2 new forms would have no tendency to sterility if acquired through Nat. Selection.—

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Gærtner Bastard s. 165 on individuals refusing to cross.— Seeing Primulas & Linum & neuter Hymenoptera & Neuroptera no difficulty in sterility being acquired, if this view would explain facts.— It would, I think, apply to all offsets of one species in same country.

The Verbascum & Tobacco case shows incidental in some cases.—

(all the facts about Lobelia — Passiflora &c & Crinum crossing more readily with another species (this cannot be dimorphism) shows how much easily reproductive system is affected by conditions of life & rendered self sterile.) (Such cases as Rawsons' Gladiolus must be different case, ie good of crossing with distinct individual.

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I suspect it will come to this that generally when a new form is selected within the same country with its parent, from early start sterility must be selected.— The vast diversity in degrees of sterility is compatible with it ensuing from various varieties — correlation, as well as selection.— Cases are on record of women sterile with one man & not with another.

Nov. 18' 1861. We must look at selection from an (say) aquatic form steadily going on; but always related till sterility is at same time gained.—

I suspect this sterility must be habitually acquired before instinctive dislike acquired; otherwise this instinctive dislike would have been potent

by itself & sterility would have been superfluous. Instinctive dislike perhaps does come much into play— see multiple origin of domestic animals — — Those that pair for life seems greatest difficulty.—

With respect to show modification like our Race-horses. Tendency to sterility may be inherited from former process of selection