150 THE SIMPLEST ANIMALS — PROTOZOA 
LABORATORY STUDY OF PROTOZOA 
Take a drop of water from an infusion rich in Protozoa; place on a 
slide and examine with a 16 mm. or f objective. Answer the questions 
suggested by the report. 
Number of 
Kinds 
Observed 
How Many Kinds — 
How Many Kinds 
Have — 
are free 
swimming ? 
are 
attached 
by threads ? 
have even 
motion ? 
have zigzag 
motion ? 
constant 
form ? 
varying 
forms ? 
127. Protozoa and Alcohol. — Scientists have studied the 
relation of alcohol to the life processes of Protozoa. Nor¬ 
mally, such Protozoa as Paramecia divide a regular number 
of times each day. When a small amount of alcohol is 
placed in water containing Paramecia, the normal rate of 
fission is diminished. Professor Woodruff has shown by an 
extended and critical study that alcohol tends to prevent 
Paramecia from dividing as many times as they would under 
normal conditions. This means that alcohol hinders the 
growth of Paramecia. 
SUMMARY 
Protozoa are the simplest group of animals. They are 
found mostly in water, yet some are parasitic in higher 
animals. They are small and usually consist of only one 
cell. They reproduce mostly by fission. Some produce 
diseases in man and beast, such as malaria and the sleeping 
sickness of Africa. But the great majority of Protozoa are 
not harmful. 
