Fig. 1. of Plate I. represents the _Noctiluca_ magnified one hundred times. Fig. 2. of the same, represents the appearance of the creature when luminous, and only slightly magnified. The long lash which extends from the side is the locomotive organ. It is attached to the body near what is supposed to be the mouth; though these creatures are so simple that many kinds, just below in organization, have no definite mouth nor stomach, but absorb food from any surface of the body which comes in contact with it. This infusorian and most potent of living lights, albeit of extreme minuteness and simplicity as an organism, is abundant in the ocean along the European shores, and is often seen in our north-eastern waters, notably off Portland harbor and along shore to Cape Ann. I have enjoyed the privilege of witnessing the fullest glory of this little creature’s effulgence. In our so-styled ocean firmament these living asteroids shine forth in those waters, and rival, if not excel, in light-giving any other known creature. In the endeavor to study the mysterious lights, I spent considerable time on a rocky point which jutted out into the sea, at Ogunquit, Me., with my microscope at hand, as near as possible to the water; thus examining them while comparatively fresh from the sea. In taking up the little creatures, they assume a pear shape, from contraction,--the only evidence, seemingly, of life, but blazing with a flashing light over their entire surface. We had the advantage of having specimens fresh at hand, yet there are certain appliances indispensable for such work which we did not have, and, therefore, could not then perfect our dissections sufficiently to get satisfactory results. We must refer the reader, therefore, to the experiments detailed in the Appendix.[1] In watching the light of the _Noctiluca_, we are reminded of the flash-light of a light-house,--the gleam appearing and disappearing with considerable regularity. It is difficult to trace the light to any particular portion of the body. In Plate I., Fig. III., is shown the supposed luminous organs, which would seem to show that there are luminous spots. Sometimes the light seems to pervade the entire body; again, to be in the outer skin or cuticle. When the light appears after an intermission, the spots referred to become luminous first, the light extending to the outer surface.