Studies on pigment-activating substances in animals I. The separation by paper electrophoresis of chromactivating substances in arthropods

Abstract
It has been established that many substances can bring about a change in position of pigments in crustacean chromatophores (Florey, 1951). The extracts of certain animal tissues (pituitary, crustacean sinus-gland and post-commissure organs, insect brain and corpora cardiaca) are especially active (Brown, 1940; Knowles, 1953; Dupont-Raabe, 1952; Thomsen, 1943); there is evidence that these tissues intervene in the normal colour change of the animals which possess them and that their products may properly be considered as hormones. On the other hand, many species which do not themselves possess chromatophores (oligochaetes, molluscs, and many insects) have nevertheless been shown to contain substances in their tissues which will, after injection into crustaceans, initiate pigment movements (Scharrer, 1954). It has not yet been ascertained whether these pigment-activating substances chemically resemble normal colour-change hormones or whether the pigment movements they produce are pharmacodynamic effects irrelevant in the study of colour physiology.