GENUS AMCEBA— AMCEBA VILLOSA. 63 



or process of variable form, but mostly rounded, knob-like, or discoid. 

 Endosarc as in Amoeba protcus, and containing usually nearly centrally a 

 single large conspicuous nucleus, and habitually posterior to this a single 

 large and conspicuous contractile vesicle. 



Size. — To ith of an inch (Wallich). 



Locality. — E n gland, France. 



Amoeba villosa, a large and remarkable species, described by Dr. 

 Wallich, was discovered by him in England. It is cliiefly distinguished by 

 its habitual more or less clavate or palmate form, differentiated into an 

 anterior broader, and a posterior region terminating in a villous area or in a 

 villous knob. It commonly projects comparatively few short thick digitate 

 pseudopods, which are directed forward and little disposed to branch. Like 

 Amoeba proteus, it ordinarily possesses a single large nucleus more or less 

 central in position, and behind this an equally large contractile vesicle. 

 Besides these, the granular endosarc contains crystals, vacuoles, oil-like 

 corpuscles called by Dr. Wallich ' sarcoblasts,' and other bodies called 

 ' nucleated corpuscles.' The food materials commonly observed are like 

 those of Amoeba proteus. Some of the specimens, according to Dr. Wallich, 

 attain a diameter of ith of an inch. 



I have not been so fortunate as to meet with positively characteristic 

 specimens of Amoeba villosa, though a similar form is frequent in many of 

 our ponds, which appears to be a different animal, and is the subject of a 

 later chapter, under the name of Pelomyxa villosa. 



Small Amoeba? are frequently to be met, in many positions or different 

 kinds of localities, which I have suspected to be the young of Amoeba 

 villosa, but of this view I have no certain evidence. They have the same 

 general form, constitution, and habits as the little Aincebse supposed to 

 pertain to Amoeba proteus, and differ only in the habitual possession of a 

 terminal villous process. 



Some water, with ooze and conferva?, collected from a brick-pond, near 

 Swarthmore College, in the autumn, was preserved during the winter In 

 February, a yellowish green dust-like film covered the surface, consisting 

 of unicellular alga?. With these, and feeding on them, there were numer- 

 ous small active Amoeba?, such as are represented in figs. 4-10, pi. VIII. 

 They commonly exhibited a clavate shape, often modified by lateral pseu- 



