GENUS AMCEBA— AMCEBA PKOTEUS. 37 



Not infrequently it assumes more or less grotesque shapes, in which almost 

 every conceivable likeness may be imagined. 



Usually Amoeba proteus creeps along surfaces, mainly extending its 

 pseudopods, and advancing in the same general direction. The pseudopods 

 may, however, be extended or produced in any direction, and in their pro- 

 duction the direction of motion of the animal may be completely reversed, 

 or it may occur in the direction of extension or production of any pseudo- 

 pod. There is no fixed distinction or differentiation of parts or regions, 

 and any point of the animal may become central or peripheral, forward or 

 backward, or lateral. 



In the movements of Amoeba proteus, as certain of the pseudopods 

 are extended, and the mass of the body is proportionately reduced, other 

 pseudopods may more or less gradually recede and merge into the advan- 

 cing ones, or they may become shriveled and mammillary in appearance, as 

 is frequently the case with the posterior extremity of the body itself, and 

 as represented in figs. 3-7, pi. I. 



The mammillary appearance assumed by the posterior extremity of 

 the animal may persist for a considerable time, though undergoing con- 

 tinued variation. Any of its processes may become the source of new 

 pseudopods, and the whole may, at any moment, contract and merge into 

 the general mass of the body. 



When Amceba proteus is free and floating or suspended in water, it 

 often assumes a more or less radiate or stellate appearance, with the 

 pseudopods more or less tapering, and it then looks like a giant form of 

 Aiiioiba radiosa, as represented in fig. 2, pi. II. 



When creeping on flat surfaces, the bod)' and pseudojiods of the 

 Amceba are more or less depressed; but when the animal is floating, they 

 are more rounded. 



The ordinary shape of the pseudopods is digitate or finger-like, or 

 depressed cylindroid, with blunt rounded ends. They may be straight or 

 more or less curved, even or crimped, and simple or branched. Sometimes 

 they are more or less tapering and bluntly pointed, or they may be clavate, 

 or thicken in approaching the end. 



The projection of the pseudopods is always preceded by a flow of the 

 more hyaline portion of the protoplasm of the body, or of the ectosarc, 

 followed closely and incessantly by an influx of the endosarc. The flow 



