58 
LABORATORY EXERCISES 
Make four or five drawings as rapidly as possible to show the 
changes which occur in its form. 
II. Structure. Study the protoplasm of the body. Why is an 
amoeba a difficult animal to see? Note that the outer layer is 
almost perfectly transparent and free from granules. This is 
the ectoplasm. Compare with this the granular central mass, the 
endoplasm. Find one or more clear spaces. These are vacuoles. 
Watch them closely. The one which disappears is probably the 
contractile vacuole. The others are food vacuoles. These sometimes 
contain foreign bodies which have been taken in for food. Find 
the nucleus. This is a round body which is denser than the rest 
of the endoplasm and appears to be slightly darker. 
III. Movement. As the animal moves, observe the formation 
of the false feet {pseudopodia). Do these appear in any regular 
manner? Watch the flowing movement of the granular part of 
the amoeba. How is this movement related to the formation of 
the false feet? 
IV. Food Getting. Add a little powdered carmine to a drop of 
water containing amoebae. Under the high power, note whether 
any of the particles of carmine are taken in by the amoebae. 
Describe the process if you see it. (Powdered carbon may be used 
instead of carmine.) 
EXERCISE 63 (Supplementary) 
THE PARAMECIUM 
The paramecium, like the amoeba, is a one-celled animal, but 
it is a free-swimming organism which is further advanced in the 
scale of life than the amoeba. It is found in fresh water ponds and 
streams. In the hay infusion previously prepared, you may find a 
scum which, when closely examined, is seen to be composed of 
many minute white objects, barely visible to the naked eye. These 
are probably paramecia. Can you explain the presence of these 
animals upon the surface of the infusion? Study the paramecia in 
