Fungi belonging to the chytrid family Physodermataceae in an increasing number of instances are known to produce two very different types of plants, (1) a stongly polycentric, endobiotic thallus which bears numerous "turbinate organs" and resting spores and ramifies through many cells of the host, and, (2) a monocentric, epibiotic "ephemeral sporangium" with a short, bushy rhizoidal system within a single host cell. The latter plant, derived from a zoospore from a germinated resting spore, gives rise to motile swarmers which are discharged inoperculately, its sporangium rests on a a broad base, is usually internally proliferous, and nearly always bears on it an unexpanded portion of the spore cyst from which it has arisen. This often gives a somewhat humped or gibbose appearance to the whole structure. In a true species of Physoderma, the ephemeral sporangial stage is completely invisible to the naked eye, in contrast to the endobiotic one which produces streaks, pustules, galls, etc. on the host plants.