ON CERTAIN REMARKABLE PHENOMENA PRESENTED BY THE COLOURED BLOOD-CORPUSCLES OF THE FROG.—Repeated observations tend to show that the structure of the coloured blood-corpuscle is by no means so simple as is usually assumed: and from this point of view the observations made by J. Gaule in Prof. Lud-wig's laboratory at Leipzig (Archiv für Physiologie, v. Du Bois-Reymond, 1880) are of singular interest. On diluting the fresh blood from a vigorous frog with 0.6 salt solution, and exposing it after rapid defibrination to a temperature of 32°–36° C. on the hot stage of the microscope, the escape of a peculiar body may be observed in many of the corpuscles. The bodies thus evolved simulate worms so closely by their form and wriggling movements, that Gaule styles them “Würmchen,”which may be translated vermicles. However, he concludes from several reasons that they are simply protoplasmic portions of the corpuscles, which, under these special conditions, separate for a short independent life. He makes no reference to previous workers in the same field; but it would seem not improbable that his “Würmchen”correspond with the maculæ, which Prof. Roberts of Manchester revealed seventeen years ago by treating the corpuscles with tannin or magenta, reagents which would of course prevent any further signs of life in the objects. The “vermicles” are about half the length of the red corpuscle, pointed at either end, but more in front, and containing one or two vesicles or droplets. Their singular movements deserve a rather full description. After wriggling out of the corpuscle, in which it makes its appearance as a rod-like body beside the nucleus, the “vermicle”moves on, trailing the corpuscle behind by a long thread. On meeting a second corpuscle it bores into it, withdraws, pushes it aside, and goes on carrying this too in its train; and though the threads finally give way, “vermicles”may be seen dragging three, four, or more corpuscles after them. The corpuscles, quitted or attacked in this way, undergo in a short time changes of form and colour leading to complete disorganisation, which otherwise, under similar conditions, require hours for their accomplishment. Finally the “vermicle”also undergoes disorganisation. While the conditions given abve are found on the whole most successful in bringing about these results, Gaule indicates limits of temperature and dilution within which they often occur, usually with slight modifications. It is this variation with the conditions of the experiment that, supplies one of his strongest arguments against the previous Individual existence of these bodies.