ONE-CELLED ANIMALS AND SPONGES. 117 
under the microscope looks like a drop of moving jelly 
of irregular outline. The greater part of the Amoeba 
is granular in structure, being surrounded by an outer 
film of clearer jelly. In the midst of the cell is a 
nucleus , a little more opaque than the rest of the cell 
but made of the same substance. The jelly-like sub¬ 
stance of which the whole Amoeba is made is called 
Fig. 99.—Forms of Amoebae (highly magnified). 2 and 3 were drawn 
from the same specimen; 5, 6, 7, and 8 were drawn from another 
specimen; A r , nucleus; P, pseudopodia. 
protoplasm. The same substance is found in the cells 
in our own bodies, as well as in the living cells of other 
animals and plants. Every plant and every animal 
begins its life as a single cell of protoplasm. Within 
the Amoeba’s cell may be also seen a round clear spot 
which from time to time contracts and temporarily dis¬ 
appears. This is called the contractile vacuole. 
