My dear Sir

I have to thank you for your very kind letter of January 12^th as well as for some copies of Mr. Meldola’s “Entomological Notes bearing on Evolution”. I enclose some additional notes bearing on the same subject, which may perhaps interest yourself or Mr. Meldola.¹

From seeds gathered in Dona Francisca I raised some plants of a sensitive Mimosa, which are as yet very small; I observed them some days ago whilst it was raining (and had been raining for many hours), but not very hard, the temperature of the air being 22^o C. The leaflets were half-closed, but the secondary and primary petioles in their normal erect position. The leaflets were in a rather insensible condition, a strong touch being required to cause them to close completely. Touching but slightly the pulvinus at the base of the main petiole, it bent rapidly down, so that its sensitiveness appeared not to be impaired.² Being rather unwell that day, I could not stay long in the rain and must delay a more thorough observation to another time.

When, long ago, in Butler’s Catalogue of the Satyridæ in the Brit. Mus. I saw (Pl. V fig 3) the elegant mane on the underside of the front-wings and the strangely modified neuration of the hind-wings of the male of Antirrhæa (or Anchiphlebia Butl.) Archæa, I felt sure, that these modified nervures must be environed by a highly developed odoriferous organ.³ Lately I have caught some specimens of both sexes of this butterfly, and indeed the male has a very strong odour emitted by the mane of the front-wings, and a very interesting odoriferous organ exists just where I had supposed it to exist on the hind-wings, besides another smaller one between the submedian and internal nervures. It is curious that in this butterfly the production of the odour appears to be almost exclusively limited to the hind-wings and the emission to the front-wings. A small oval opake spot in the membrane of the front-wings appears to be an odoriferous organ in a very rudimentary condition.

Among moths the legs appear to be in a large number of cases the seat of odoriferous organs in the form of pencils, tufts, brushes etc. attached to the femur or tibia, of fore, middle or hind-legs. In one very common moth a large tuft of hairs is situated on either side of the prothorax, close to the insertion of the coxæ of the fore-legs; when these legs are extended and moved forward, the tuft of hairs unfolds into a large cone. You know that among butterflies the males of some Hesperidæ have large pencils of hairs on the tibiæ of the hind-legs and in the case of Plesioneura Eligius (named for me by D^r. Staudinger) I meant to perceive a faint odour emitted by these pencils, when unfolded.—⁴

I have lately tried to raise caterpillars from eggs extracted from the abdomen of female butterflies. The main difficulty consists in finding a proper food-plant for the young caterpillars, but generally the caterpillars of nearly related butterflies feed on the same or on nearly related plants. Thus, knowing that the caterpillars of Anartia Amalthea, Victorina Trayja, and Eresia Langsdorfii live on the same Acanthaceous plants, I gave the same plants to a young caterpillar of Junonia Lavinia and they were not rejected. The caterpillars of those four species resemble each other so perfectly, that in a system of caterpillars they would no doubt be united into a single genus.⁵

Some time ago I found on the leaves of Passiflora quadrangularis eggs of a butterfly, which evidently belonged to some Heliconius or any allied species. The young caterpillars died—(to my great surprise, for I had raised plenty of Heliconinæ from the egg)—one after the other without touching the leaves, on which the eggs had been found.⁶

At last, when only one survived, it occurred to me that their mother might have deposited her eggs on a wrong plant. For, though based on a far more solid ground, than that of the pope, the infallibility of butterflies also is not absolute. In consequence I placed before the starving caterpillar leaves of various other species of Passiflora at my disposition and before long it began to feed on one of them. By the choice, it made, I immediately supposed, that it would be a caterpillar of Dione Vanillae and this afterwards proved true.⁷

We are now prisoners here, having the yellow fever on the sea-shore of our province, by which circumstance our postal service also has become extremely irregular. To give an instance, I received in due time N^o 432 of Nature; ten days after N^o 430 and 433 arrived and only after another fortnight I received yesterday N^o 431.⁸

On my late excursion to São Bento I saw a white Niata cow, which contrary to what you observed, was extremely tame.⁹ I would have liked very much to possess this interesting animal; but they would not sell her.

Pray, recommend me to your son Francis¹⁰ and believe me, dear Sir, with sincere respect | yours very faithfully | Fritz Müller.