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July 3d 1869.

Variability under nature

Important

I think it agrees best with what we see under Dom. that characters become & long remain fluctuating, & only occasionally actually new characters parts appear.— By Pangenesis we can understand that changed conditions have affected affinities of tissues & gemmules.—

That conditions are concerned in causing var[iet]y we may infer from domestication & monstrosities & sports or modifications; & from the same species varying more in one locality than another — New effect of chemical composition Lawes & Gilbert — it is absurd to say that plants growing ever closer together can expand to same conditions & their parents before them.— Again plants in New Zealand being so variable — & this agrees with fluctuations of characters long remaining. Again all sp. of Rubus, are descended from 1 progenitor & yet some few sp. are not highly variable — How about Hieracium, Cirsium &c ask Nägeli? Again I think most protean genera are large — Is not Epigæa of Meehan an exception? & this wd indicate that variability is caused & is inherited, & there is evidence from Hybrids that variability itself is transmitted, & this is just as possible as Trimorphism or Dimorphism being transmitted— (over

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Again I am nearly sure that same species is variable in one region & not in another — Nägeli gives instances of this, & I think I have many recorded — if so not one innate property — This is so very important since the extent causes do not directly cause each particular modification — but induce general variability by affecting the elective affinities for special gemmules —

With respect to the fixing of fluctuating character case of Dorking fowl cd lead to support the effect of selection, or of long-continued potent external conditions.— Fluctuation of character was seen in Hybrids of successive generations, but mingled under Dom & true variation, with new characters.—

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In case of N. Zealand introduction from some very dissimilar country & wide spreading & will apparently alone explain polymorphism of so many genera.—

In case of Rubus, the progenitor must either have been either constant or polymorphic, & in either cases some of the descendants have become either constant or polymorphic, & this is opposed to innate tendency.—

With respect to similarity of conditions, which one dead animal wd modify soil, & especially nature of surrounding plants wd govern the power of any one getting the elements.—

Explain fluctuation — when 2 vars of pigeon crossed colours &c &c blended & piebald — I do not know how physiologists look at this — according to Pangenesis — gemmule — so with a polymorphic species not crossed I look at affinities between gemmules & tissues as disturbed —perhaps probably unequally collected by reproductive organs —

In addition parts really modified.— over

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Can many forms ever be of any adaptive base to a species like the 3 forms with trimorphic plants?—