[163]

Perhaps important — Dec. 18 — 62.

Wth formation of Marsh var. of a Plant, it wd not be necessary that it shd be sterile with land var, only that it produced rather more seed with Marsh var. & the result would be that the marsh var, having slight advantage of habit & greater fertility would gain the end. This tendency which is in fact all that occurs in once fertile hybrids & 1st crosses then might be selected or go on aggregating by simple effects of conditions. ─ (over)

A closely interbred dog, I have heard several cases, wd not breed with its own kind, but did freely with mongrel— This seems to show how easily generative system modified.

Possibly — not sure foal-getter may not be perfectly fertile with certain individual females, but not with all. —

[163v]

Suppose a short-beaked var & long short-beaked var, when paired produced on average a few more percentage of young ones than a heterogeneous pair — this would clearly be advantage— (like seed in wheat field) & so onwards. — Those which produced most young when matched would necessarily prevail— & of these subject to other contingencies. —