Verworn (1889, p. 40) studied the movements of Amoeba limax and A. princeps in a microspectrum and in a field of white light with sharp gradation of intensity and maintains that they crawled about from one color to another in the spectrum and from one intensity to another in the white light without any apparent reaction. In both cases the rays were perpendicular to the slide on which the amoebae were mounted. Davenport (1897, p. 186) also failed to obtain reactions in Amoeba proteus in white light under similar conditions, but he showed very clearly that these creatures orient and move from the source of illumination if they are exposed in a horizontal beam of intense light so arranged that no other light reaches them. This led him to conclude that the reactions in these organisms are due to the direction of the rays and not to difference of intensity. Rhumbler (1898) observed that sudden illumination causes a cessation in activity in Amoeba verrucosa feeding on filaments of oscillaria. Harrington and Learning (1900) found that intense white or violet light thrown on an active specimen of Amoeba proteus causes the protoplasmic streaming to stop instantly. Red, on the other hand, they claim, causes an acceleration in movement, while green and yellow have very little effect. Engelmann contends (1879) that intense illumination causes the rhieopod Pelomyxa to contract. Ewart (1903) says that it causes a retardation or cessation in the protoplasmic streaming in many different plant cells. And both Baranetzski