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Linn. Trans v. 17. p. 139. D. Dod on the Æstivation in certain Plants"— depends in great measure on the relative position & development of the organ of reproduction ((so that one can see how change might be affected.) — in monopetalous plants æstivation is character of very high value & affords only palpable character in separation of families. But the Bubiaceæ offer marked exception, examples

Does aestivation vary in old genus Cinchona?

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of almost every form of æstivation being afforded by it. "The Rubiaceæ appear to constitute a grand central point of union (of which several may be remarked in the vegetable kingdom) between the families of the monopetalous class & possessing great diversity of characters, they partake more or less of the habit & structure of those orders to which they are most related, so various is æstivation in the Rubiaceæ, that in old genus Cinchona examples of each variety may be found. (Does the convolute valvata æstivate, in duplicate blend æstivation blend into each other?? they ought to do by my theory.)─