Dr. Leidy lately described to the Academy of Sciences in Philadelphia an encounter for life which he witnessed between two microscopic animalcules. The two creatures were respectively 1-625th and 1-200th of an inch in diameter. On the morning of August 27, from some mud adhering to the roots of sphagnum, obtained the day previously in a nearly dried-up marsh at Bristol, Pennsylvania, he obtained a drop of material for examination with the microscope. After a few moments he observed an amoeba verrucosa, nearly motionless, empty of food, with a large central vesicle, and measuring 1/25th of a millimetre in diameter. Within a short distance of it, and moving directly toward it, was another and more active amoeba, regarding the species of which he was not positive. It was perhaps the one described by Dujardin as amoeba limax, by which name it may be called. As first noticed, this amoeba was one-eighth of a millimetre long, with a number of conical pseudopods projecting from the front border, which was one-sixteenth of a millimetre wide. The creature contained a number of spherical food spaces with sienna colored contents, a large diatom filled with endochrome, besides several clear food spaces, a posterior contractile vesicle, and the usual glanular endosarc. The amoeba limax approached and came into contact with the motionless amoeba verrucosa. Moving to the right, it left a long finger-like pseudopod curved around its lower half, and then extended a similar one around the upper half until it met the first pseudo-pod. After a few moments the ends of the two projections actually became continuous, and the verrucosa was enclosed in the embrace of the amoeba limax. The latter assumed a perfectly circular outline, and after a while a uniformly smooth surface. It now moved away with its new capture, and after a short time what had been the head end contracted and became wrinkled and villous in appearance, while from what had been the tail end ten conical pseudopods projected. The amoeba verrucosa assumed an oval form, and the contractile vesicle became indistinct without collapsing. Moving on, the amoeba limax became more slug-like in shape. The amoeba verrucosa now appeared enclosed in a large oval, clear vacuole or space, was constricted so as to be gourd-shaped, and had lost all trace of its vesicle. Subsequently it was doubled upon itself, and at this point the amoeba limax discharged from one side of the tail end the siliceous case of the diatom, which now contained only a shrivelled cord of endochrome. Later the amoeba verrucosa was broken up into fine spherical granular balls, and these gradually became obscured and apparently diffused among the granular contents of the entosarc of the amoeba limax. The observations from the time of the seizure of the amoeba verrucosa to its digestion or disappearance among the granular matter of the entosarc of its captor, occupied seven hours. From naked