at the Lycée. 1867-76: Return to the Itajaí Valley as a minor provincial official. Worked as a botanist and as an advisor to farmers. 1876-91: Travelling naturalist of the National Museum. Explored throughout the Itajaí system. Dismissed by refusing order to live in Rio de Janeiro. 1891-97: Last years; visited 1890-93 by cousin Alfred Möller. Biology During his life Müller published over 70 papers, mostly in German-language periodicals, some in English and Portuguese. The topics covered a range of natural history topics: Entomology Termites Hymenoptera: ants and bees Lepidoptera: butterflies and moths Marine zoology Crustacea Botany Excursions and surveys throughout Itajaí river system. Collected seeds and specimens; exchanged seeds with Joseph Dalton Hooker at Kew Gardens and sent specimens. Pollination in orchids Climbing plants Müllerian mimicry. Müller's great discovery concerned the resemblance between two or more unpalatable species which are protected from predators capable of learning. The protection is often a noxious chemical, perhaps gained from the larva eating a particular plant; or it may be a sting or other defence. It is an advantage for such potential prey to advertise their status in a way clearly perceptible to their predators; this is called aposematic or warning coloration. The principle is of wide application, but in Muller's case the prey were butterflies, and the predators usually birds or reptiles. The aposematic colours are most often some combination of red, yellow, black, white, whereas palatable animals are usually cryptic. The noxious animals may display by slow flying, and in general are prominently visible. Noxious animals usually have thick, leathery cuticles through which, at certain points, they extrude noxious fluids when pecked; they will often survive a 'trial'. In Müllerian mimicry an advantage is gained when unpalatable species resemble each other, especially when the predator has a good memory for colour (as birds, for instance, do have). Thus one trial may work to dissuade a bird from several species of butterfly which all fly the same 'flag'. Brazilian butterflies provide some of the most extraordinary examples of mimicry, and Müller, Bates and Wallace all had lengthy experience of this. All three traveller-naturalists believed firmly that such systems of mimicry could only come about by means of natural selection, and all of them wrote about it. Müllerian bodies in Cecropia. Müller was able to show that the small bodies at the petiole-bases of Cecropia are food bodies and are used by protecting ants