PHAGOCYTE (from Gk. /ar,eIv, phugeht, to eat + Korot, kyfos, hollow. eell). A microbe-de struying cell residing free in the animal system. About 18S3 Alctehnikoif found that the individual cell. I If the stomachs of sponges took in solid par ticks; of food and digested them, and this he called intracellular digestion. This function is performed by individual, free, or 'wandering' mesoderm cells, resembling amoeba•. Such wan dering cells, in the eases of many of the lower animals, ingest or absorb parts of the body which become useless or by decay harmful to the organism. Besides this these free anneboid yells can and do capture and devour foreign bodies and particles; they take up anything hard or soft which occurs in or is carried into the body; and when such cells are confronted with a large mass of food-material. which they cannot devour singly, they usually fuse into a plas modium, Which eats up the whole available food. Such bodies as cannot he eaten are sur rounded and isolated. Led by these facts, Metchnikoff threw out the remarkable theory that inflammation in the vertebrates is due to the struggle between the white corpuscles of the blood and the within it. Thus a new importance was lent to the leueoeytes or white anneledd corpuscles, viz. that they act as
microbe-eaters or 'phagocytes.' Aletchnikoff in jected fluids containing bacteria or microbes be neath the skin of various invertebrate animals. They were soon found within the anraboid cells, if such microbes developed spontaneously in the wounds of such animals, they were absorbed in the same manner. Kovalevsky, a few years later, made similar observations in eomponnd aseidians. When an individual died it was at tacked and absorbed by the mantle cells of the colony, which also sought to destroy incoming bacteria, as was proved by experiment. Nova levsky concluded that the passage of the wander ing yells to the surface of the epithelium is a means of protection against the intrusion of agents of disease. These discoveries and theories mark an epoch in biology in its application to medical knowledge.
Bunt.roonANIY. 'Met chn i kW, "Researches on the 'Intracellular Digestion' of Invertebrates," 011ffrirr/r/ Journal of .11 icoAcopical vol. Nsiv. (London, 1Ss4) ; /.,(coils stn• 10 comparee de l'inflenunation, foil es it at PaRleur en aeril et mai 1891 (Paris, 1S911.