The central part of the fecal stone consists of the feces, having lime and fibrin. The layers of the fecal stone consists of fecal, lime and fibrin layer. The thickness of each layer, however, are not constant and moreover, different even in the smae layer, thus making sometimes imperfect circle. The extremely outer surface of the stone has mostly cellular layer or fibrin network. Many parasitic ovi were found in the fecal layer, but the possibility for them to be the factors of nucleus formation could hardly be considered.