The ridges in _proteus_ recall, of course, the ridges always observed in _verrucosa_, _sphaeronucleosus_ (Figure 13) and their congeners, especially while the latter are in locomotion. A _sphaeronucleosus_ is especially favorable for study in this connection because of its greater activity. This ameba has four or more longitudinal ridges on its upper surface, while in locomotion, which strongly resemble those in _proteus_ and _carolinensis_. The chief difference lies in the fact that in _sphaeronucleosus_ the ridges are extended at their anterior ends continually, and unless the direction of locomotion is changed, the ridges may retain their identity while the ameba moves several scores of times the length of its body. Along the sides, however, new ridges are continually replacing older ones. When the direction of locomotion is changed, the old ridges usually all disappear into a jumble of ridges and crinkles running in every conceivable direction, and with the reestablishment of locomotion along a more or less straight path, a new set of ridges appears. In _sphaeronucleosus_ and its congeners, the ridges are also not wrinkles, but ridges that are formed later than the surface contiguous to them. It is interesting to recall also that the ectoplasm in _sphaeronucleosus_, _verrucosa_ and the rest of this group, is much firmer than in most other amebas. CHAPTER V PSEUDOPODS AND THE NATURE OF THE ECTOPLASM In contrast with the ridge-forming amebas stand those with smooth ectoplasm, such as the common _dubia_, _discoides_, _villosa_, and the rarer _laureata_ and _annulata_, to mention only a few of the larger forms. In addition to these may be mentioned all the pelomyxas and nearly all the smaller amebas. Much the larger number of species of amebas do not form ridges in the ectoplasm during locomotion. [Illustration: Figure 4. _Amoeba laureata._ This ameba is multinucleate, containing a thousand or more nuclei of the shape shown at the right. Ameba 1000 microns long in locomotion. Nuclei 10 microns in diameter.] Of all the amebas with smooth surfaces, the most favorable for observation as to the formation of ectoplasm, is the giant _laureata_ (Figure 4), though it is unfortunately of infrequent occurrence. This species is as often found in clavate form as with pseudopods. In cross section it is circular or nearly so. It is often found with _zoochlorella_ growing in it, upon which it seems to depend largely for food, for it seldom has distinctive food masses in it. The nuclei are small and very numerous and the crystals are well formed and numerous, each in a small vacuole, and of a size about two or three times those found in _proteus_. It will be seen therefore that there are only small bodies in this ameba, none of which (excepting the contractile vacuole) are large enough to change the course of the endoplasmic stream, and streaming is thus reduced to what might be called a typical condition.