It has been well known that the normal skin of silkworm larvae is opaque and white in colour and contains a large amount of uric acid in the hypodermis. In the oily skin mutant, however, the skin of larvae is more or less translucent and contains small amount of uric acid. So it provides a very interesting problem whether the skin becomes translucent if one could expel uric acid from hypodermis of normal larvae. In the course of an experiment to induce oily skin phenocopy, we confirmed that all of the normal larvae which were given melamine, 2, 4, 6-triamino-s-triazine, turned into translucent skin within two or three days. This may be thought as phenocopy in the sense that originally normal individuals change into mutant-like feature. But this is somewhat different from usual phenocopy produced by abnormal differentiation of rudiment, and it is to say that this is a new type of phenocopy. In this induced oily skin, too, uric acid content of hypodermis is so reduced to remain trace of the acid that the rest of it is excreted out. Melamine does expel not only uric acid but also such pigments as xanthopterine-B, yellow pigment of the lemon character, and neutral red from some tissues and organs as hypodermis, silk glands, testes and so on. Thus it may be inferred that the protein in hypodermis functions as a storage protein biophysically accumulating uric acid. And it may also be conjectured that hereditary oily skin characters are manifested by the abnormality of the protein which accumulate uric acid in the hypodermis. Up to present, melamine is the only substance which can induce oily skin phenocopy, and this function of expelling uric acid and pigments out of tissues may be called as "melamine effect."