Summary

Describes his experiments in fertilising Oncidium flexuosum and comparison with Notylia.

Has been examining Catasetum.

Encloses seeds of two species of Gesneria and describes hairs in the seed capsule. Hairs in other plants seem to have a different function.

Starting tomorrow for a botanical excursion on the Continent.

Summary

Studying self-sterility, particularly in Oncidium, where abortion occurs consistently but stigma functions normally. His hybrid orchid crosses show sterility occurs capriciously. Thus it is not a "special endowment".

Disputes Asa Gray’s and Hermann Crüger’s view of rostellar germination.

Doubts absolute sterility of Catasetum.

Disappointed by results with homomorphic cowslips.

Summary

Wants to hear from readers about the way in which the bee-orchid (Ophrys apifera) is fertilised. He has always found it to be self-fertilised but greatly doubts that the flowers of any plant are fertilised for generations by their own pollen. The bee-orchid has sticky glands, which would make it adapted for fertilisation by insects; this makes him want to hear what happens to its pollen-masses in places he has not observed.

Summary

Reports observations on fertility of orchids he has self-pollinated and crossed with pollen of other species.

Summary

Describes variability in the stamens and pollen of Lagerstroemia, which CD spoke of in Forms of flowers.

Also reports on similar phenomena in Pontederiacea (Heteranthera reniformis).

Has received from Paul Mayer an interesting paper on metamorphosis in Palaemonetes varians, which is also being studied by J. E. V. Boas in Denmark. Shows differences between larval development in Danish forms and those found in southern Italy.

Summary

Apologises for not having answered CD’s letters of 19 December [13564] and 4 January [13599] sooner.

Gives the results of his crossing experiments with Pontederia (Eichhornia) crassipes and P. azurea. Has also begun experiments on Heteranthera reniformis.

Thanks CD for sending three parts of the first volume of Bentham and Hooker’s Genera plantarum.

Summary

Gives observations on orchid ovules ripening long after blooming.

Infertility with own pollen sometimes does and sometimes does not indicate dimorphism; gives observations on Ximenia, Eschscholtzia and Oncidium flexuosum.

Describes some striking seeds eaten by birds,

and some new dimorphic species.

Variation in Thillia.

Confirms CD’s suspicion that the lancet-fish [Amphioxus] lives in competition with invertebrates: it shares its habitat with a similar-looking Ophelia, which is quite unlike other annelids, just as the lancet-fish is unlike other fishes.

Summary

Comments on CHB’s book [Experimental researches on catarrhus aestivus – hay-fever or hay-asthma (1873)].

Explains that some pollens are wind-blown while others depend on insects for dispersal. Effect of pollen on skin and mucous membrane astonishing. Sends a book [M. Wyman, Autumnal catarrh (1872)].

Summary

Sends drawings of the pollen from Chinese Primula plants with styles and pistils of different lengths; observations on sizes and condition of their pollen.

Summary

CD is considering repeating experiments on melastomads in which different pollen sizes produced differing seedling sizes.

Responds to JDH’s query on differences in pollen within the same species.

Summary

Instructions on measuring pollen of dimorphic plants.

Summary

Sends Passiflora paper [see 4485].

Sends seeds of peloric Antirrhinum crossed by normal form and sends results of his experiments [table of crosses].

Summary

Has reread JDH’s paper ["On the functions of the rostellum of Listera ovata", Philos. Trans. R. Soc. Lond. 144 (1854): 259–64].

Summary

Experiments to cut Laelia stigma from rostellum and then to fertilise rostellum are baffled by "a latent instinctive power". Somehow the pollen-tubes find their way to the style.

Suggests CD study variation in ferns.

Summary

Thanks for CHB’s essay [New observations on hay-fever (1877?)]. The calculation of the weight of pollen-grains is wonderful. Suggests he consult Cross and self-fertilisation, pp. 376, 405 for information on this subject.

Summary

Floral anatomy of Goodeniaceae: although flowers seem to fertilise themselves by pistil moving to anther, CD shows that insect agency is necessary. Wants JDH to check his interpretation of stigmatic surface.

Summary

Puzzled by function of orchids’ rostellum.

Orchids’ pollen concentrated in two pollinia; hence one flower can fertilise only two others. This may explain precision of orchid pollination mechanisms.

Summary

Rejects necessity of outbreeding and any general law of reversion.

Describes further experiments with Hippeastrum showing greater fertility with foreign pollen than with individual’s own pollen or with pollen from another individual of same species.

Does not believe CD’s questions about reversion can be answered in present state of knowledge.

Summary

Sends Pulmonaria anthers, with measurements of styles and pollen counts.

Summary

Believes some flowers fail to produce seed because of the access of too great a quantity of pollen. Asks for CD’s opinion and references.