Podostemaceae flowering under water.
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Podostemaceae flowering under water.
Sends JDH part of MS for chapter 3 of Natural selection ["Possibility of all organic beings crossing"] to be corrected and returned.
JDH’s report of Podostemon flowering cleistogamously under water in Bengal.
[Copious revision by JDH.]
No summary available.
His observations on Subularia: has never seen it in flower in the air.
Questions JDH on separation of sexes in trees in New Zealand flora.
Cites cases of leguminous plants whose cleistogamic flowers produce more seed than perfect flowers. [See Forms of flowers, p. 326.]
He is steadily and very hard at work on "Variation" [Natural selection] and finds the whole subject "deeply interesting but horribly perplexed".
Has done New Zealand flora calculations. Results support CD’s theory of necessity of crossing. Trees tend to have separate sexes.
Agassiz has informed him that the mice and rats of Mammoth Cave are American in type.
Alludes to CD’s doubt of the principle that "progress of life on the globe is parallel with the development in different tribes". Outlines his own ideas on the "unfolding of the type-idea" and its "parallelism with the law of development in the embryo".
No summary available.
Writes of arrangements for the end of the school-term.
Condition of Emma and the new baby [C. W. Darwin].
CD is convinced of relation between separation of sexes and tree-habit.
Recent hard blows against crossing theory.
CD long tormented by land molluscs on oceanic islands; found transport possible experimentally.
Informs CD that the "dishonest mollusks" were collected in May 1855 in Porto Santo. Describes some Madeira species. Though believing in "species" more and more, these may be "mere insular modifications".
Informs CD that in his experience with peas he has never found the seed to deteriorate.
No summary available.
On the variety of species definitions prevalent among naturalists.
No summary available.
No summary available.
Notes on the comparative rarity of intermediate forms between species, and the varying relationships those forms may have to one or both species between which they are intermediate.
His experience confirms CD’s view that some species and even some genera of Brachiopoda are consistently more variable than others, and that such variable forms are variable in all localities and at all periods. Similarly a species that shows a lack of variability does so at all points in time and space. Discusses the causes of variability. [See Natural selection, p. 106.]