DESCRIPTION OF PLATES. 127 
digests without a stomach, but it walks, or at least 
moves from place to place, without feet. This 
it does by means of what are called pseudopodia 
(pseudopods’), or false feet. These are simply pro- 
jections pushed out from the body-mass ; and move- 
ment is effected by a flowing over of the fluid 
protoplasm into the extended pseudopod, not by 
the attachment of these false feet to the surface 
along which movement takes place, and by a drag- 
ging along of the mass. 
The Amcebe are vegetable feeders, — probably 
not so much from choice, as because they have no 
means of capturing the active Infusoria which are 
associated with them in the stagnant water where 
they are commonly found. Professor Leidy has 
seen a living infusorium within the contractile 
vesicle of Amcba proteus. 
The Amoebse evidently have the power of se- 
lecting food; for when they come in contact with 
a unicellular alga or other water-plant of suitable 
size to be included within the protoplasmic mass, 
they admit it to the interior by extending pseudo- 
podia around it. These coalesce at the extremi- 
ties; and in this way filaments several times as 
long as the diameter of the body of the creature 
in repose, may be engulphed and digested. On 
the other hand, inorganic particles with which 
they come in contact receive no attention, or are 
only accidentally included when making a meal, 
and are quickly rejected. As already stated, a 
detached pseudopod becomes at once an inde- 
1 Leidy. 
