10 BRITISH FRESHWATER RHIZOPODA. 
the agency of pseudopodia. In the Amcebina, Arcellida, 
and other lobose forms, these ‘‘ changeable processes ” 
are usually few in number, short, digitate, and blunt 
at the tip; or they may be broad and lobose—in the 
Amabe they are most frequently so—whilst in the 
Euglyphe and others, included in what Leidy classed 
as the Filosa, they are acicular, sometimes short, but 
more frequently of considerable length, and capable of 
branching, and also, in a small number of forms, of 
anastomosing. These acicular pseudopodia may be 
rigid and susceptible of little apparent change for 
longer or shorter periods ; often, however, they change 
rapidly, or they may whilst fully extended (e. g. 
Fies. 2 and 3.—Examples of pseudopodia. 2.—Digitate and 
branching pseudopodia of Ameba proteus, showing also nucleus, 
(n.) and contractile vacuole (c.v.). x about 150. 3.—Eruptive 
(hernia-like) pseudopodium of Lithameba discus. 
Cyphoderia) sway to and fro, bend at an acute angle, 
or become curved, or take other forms. In some of 
the Reticularia (Proteomyxa, Ray Lankester) they 
branch out remarkably, and form a widely-spread net- 
work, which, like a spider’s web, serves to capture 
prey. This is conspicuously the case in Penardia. The 
Heliozoa in some cases (probably in most) have radial 
filaments, the centre of which is occupied throughout its 
entire length with a thread of “ stiffened protoplasm.” 
In the \mele changes of form are sometimes very 
rapid. The production of pseudopodia, or rather the 
contributing cause, has been a subject of lively con- 
troversy. The theories of the early observers were as 
