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Nectar-Secreting Organs of Plants.—In the account compiled by Gärtner ("Beiträge zur Kenntniss der Befruchtung," p. 75, 1844)¹ of the various organs in plants from which nectar is secreted, no mention is made of the stipulæ of the leaves of the common Vetch and Bean. On two occasions I have observed hive bees by the thousands industriously visiting the little dark (but sometimes colourless) glands on the under side of the stipulæ of the Vetch. On a hot day, on each gland a minute drop of nectar may be seen almost with the naked eye, and which is sometimes so large as to be just perceptibly sweet. I have seen the hive and another species of bee, a moth, ants, and two kinds of flies, sucking these drops. The hive bee never once even looked at the flowers, but attended solely to the stipulæ; whereas, at the very same time, two kinds of humble bee were sucking the flowers, and never visited the stipulæ. I noticed the hive bees on three successive hot days thus employed; but on the overcast morning of the 12th, after the previous very rainy day, not one was to be seen at mid-day, but numbers of humble bees were sucking the flowers: at 4 o'clock P.M., however, after some hot sunshine, a little glittering drop of nectar studded every gland, and the hive bees, by their mysterious means, had found it out, and were swarming all over the field. The fact of nectar being secreted by an organ quite distinct from the flower (though known in other cases) seems to me of some little interest, as showing that those botanists cannot be correct who believe that nectar is a special secretion for the purpose of tempting insects to visit flowers, and thus aid in their fertilisation.² No one probably who has attended to this subject will dispute that insects in very many cases do thus aid the act of fertilisation; but we must, I think, look at the nectar as an excretion which is only incidentally (as is so often done by nature) made use of for a further but most important object. C. Darwin, Down, Farnborough, Kent.

¹ Karl Friedrich Gärtner (1772-1850), German physician and botanist. Gärtner 1844. On this letter and Darwin's notes and observations on the habits of bees see Correspondence vol. 5, p. 383.

² What Darwin described as fertilisation is now called pollination.