Another very interesting feature of _Pelomyxa schiedti_ is the uroid (Figure 6, _u_), which in this species consists of a number of very thin projections resembling pseudopods extending from the posterior end. These projections are attached to the substratum and in some way aid in locomotion. These uroidal projections are of considerable length, and may persist for a considerable length of time. Thus while _schiedti_ is unable to form pseudopods at its anterior end, it forms uroidal projections with great ease at its posterior end. But what the conditions are which are necessary for the formation of a uroid, a structure which it may be added, exists in many species of amebas (and perhaps also in Cercomonas), is quite unknown. In contrast to the amebas thus far discussed from the point of view of the transformation of endoplasm into ectoplasm, there are a number of species in which two distinct methods of endoplasmic transformation occur typically. Among these species are the small _Amoeba radiosa_ (Figure 7), _A. bigemma_ (Figure 8) and a new species which for convenience will be referred to as _bilzi_. [Illustration: Figure 8. _Amoeba bigemma_, after Schaeffer. _a_, usual form in locomotion, showing the numerous pseudopods, vacuoles, nucleus and food body. _b_, rayed stage frequently assumed when suspended in the water. The pseudopods in this stage are clear, slender, and more rigid than those in stage _a_. _c_, an excretion sphere attached to a twin-crystal characteristic of this ameba. _d_, the nucleus, consisting of a clear nuclear membrane and a mass of chromatin granules in the center. _e_, a small sphere attached to a crystal. _f_, a twin crystal unattached to a sphere. Length of _a_, 150 microns; of _d_, 12 microns; of _f_, 2 microns.] It is well known that _radiosa_ has two stages: a more or less clavate shaped stage in which the ameba creeps along the surface of some object (Figure 7, _d_); and a stage in which a number (eight or less) of long and very slender tapering pseudopods are formed which usually persist for a long time (Figure 7, _a_, _b_). These pseudopods are frequently quite straight and regularly disposed around the central mass of protoplasm (Penard, ’02, pp. 87, 89). In no case are any endoplasmic granules found in these slender pseudopods; they consist entirely of hyaloplasm. In retracting these pseudopods a curious phenomenon is sometimes observed; the pseudopod is rolled up into several (as many as six) turns of an almost perfect helical spiral of a diameter six to eight times that of the pseudopod. But as the process of withdrawal proceeds, the spiral becomes irregular, but parts of some of the turns persist in the last vestiges preceding complete withdrawal (Figure 7, _b_). These spirals are also observed in other species besides _radiosa_ (see p. 128 seq.)