His observations on mimicry in butterflies
and self-sterility in plants.
Itajahay, Sa Catharina, Brazil
March 29. 1870.
My dear Sir
I have been detained from answering sooner your letter ofDecbr. 1st, by an excursion into our primeval forests and afterwardsby a severe illness of one of my daughters.f1 And now, I must firstexpress my cordial thanks for a copy of No 1 of “the Academy”and for the German translation of Wallace’s exceedingly interestingwork on the Malay Archipelago.f2 One of the points, which haveinterested me most in this work, is the dimorphism and mimicry ofseveral butterflies.f3 My attention having thus been calledto our endemic butterflies, I have met also with several cases ofclose ressemblance of species belonging to distinct genera, which mustprobably be attributed to mimicry. There is, for instance a verycommon Pieris (1), and three or four other rather rare species,when seen from above, are more or less closely imitating the coloursof this Pieris.—
I am much obliged for your account on Eschscholtzia;f4 the influenceof external conditions on the self-fertility of this 〈foot of page,probably containing diagram, excised〉 species is verycurious; it is shown in a striking manner by a plant, which I hadraised 1868 from your seeds and which only flowered 1869.—f5 Theother plants from the same seeds, which flowered the first year (1868)had retained self-fertility in a small degree; but this plant, whichflowered only the second year, and had thus been exposed for a farlonger time to our climate, proved perfectly self-sterile; it has beenleft uncovered, but growing at some distance from the other plants,which flowered at the same time, it produced by itself only a fewvery poor pods containing not even a single seed. Two flowersfertilised by pollen of a distinct plant yielded large pods, oneof which contained 115 seeds.—
I have been much pleased by hearing from Alex. Agassiz, thathe is now inclining to your views.f6 I think very high of him as oneof the most skilful and conscientious observers. His “Embryologyof the Starfish” is a master-piece.—f7
I gave you, in my last letter, some cases of plants, the firstflowers of which had a larger number of petals or stamens than thelater ones.f8 I have since found, in a tree of C〈assia〉 multijuja, that thefirst flowers of 〈foot of page excised〉