GENUS AMCEBA— AMCEBA VERRUCOSA. 55 



it in the ooze of ponds, ditches, and river shores, in the mud of marshes, in 

 wet sphagnum, among the confervas of fountains and dripping rocks, and 

 in company with Rotifers, about the roots of mosses, in the yard attached 

 to my house. 



Asiurba veirrucosa is exceedingly sluggish, and often, during the 

 time of its observation, remains stationary, or nearly so. In this condition 

 it usually appears as an irregular quadrately round or oval and more 

 or less wrinkled mass, with short lobate pseudopods or wave-like expan- 

 sions of the surface. The pseudopods are slowly projected, apparently in 

 a hesitating manner, and the wave-like expansions slowly but incessantly 

 change. In motion, the Amoeba glides along with extreme slowness, 

 advancing by wave-like expansions, while short lobate pseudopods project 

 in any direction, apparently without object, The whole surface of the 

 Amoeba often appears delicately wrinkled. See figs. 5-7, 28-36, pi. III. 



A striking peculiarity of Amoeba verrucosa is that the outlines of the 

 body, the pseudopodal expansions, and the wrinkles of the surface often 

 appear defined with partial or interrupted double lines, as if the animal were 

 invested with a delicate membrane. See figs. 1, 2, 7, 28, 29. 



Amoeba verrucosa is highly transparent, and colorless, and it commonly 

 exhibits an unusual degree of extension or differentiation of the ectosarc 

 from the endosarc The former appears homogeneous, but under high 

 powers of the microscope is seen to be extremely finely granular. 



The endosarc presents a diffused pale granular appearance gradually 

 merging into the ectosarc, It often contains but a scanty supply of food 

 materials, and sometimes these appear to be absent, or at least they are not 

 recognizable, as exemplified in figs, 5, 9-11, 35. Commonly, more or less 

 food is visible as pale granular, colorless or yellowish balls scattered 

 through the endosarc, as seen in figs. G, 7, 28-34. Not unfrequently alga? 

 are present, such as protococci, oscillarias, diatoms, and desmids, as seen 

 in figs. 1-3, 12-14, 30-32. In several instances I observed specimens of 

 the Amoeba containing a Trinema, or a Difflugia, or both, as seen in fig. 38. 



Generally, a nucleus is included in the endosarc, but frecpiently I have 

 been unable to detect one. 



A contractile vesicle is nearly always present and sometimes two or 

 three. In several instances I was able to satisfy myself that the Amoeba 



