4 Elementary Manual of Zoology. 
I.—PROTOZOA. . 
The chief point to remember about the Protozoa is that they are 
animals which each consist of only one cell. Each Protozoon therefore 
may be appropriately compared to one of the vast army of cells, of which 
the tissues of allthe higher animals are built up. Inits simplest form 
a Protozoon consists of a little speck of transparent jelly (protoplasin) 
with a nucleus of denser matter. This simple structure is often obscured 
by shells of chalk or flint and other matters secreted by the jelly. The 
students will be able to examine a few of the common forms of Protozoa 
for themselves, through the microscope (see practical work). The fol- 
lowing may be noticed : 
(1) Ameba.—This is a minute speck of jelly-like protoplasm 
which crawls alonz instagnant water. Its movements are 
effected by the protrusion and retraction of little finger- 
‘like processes of the jelly which are known as pseudopodia. 
It feeds by encircling food particles, which it meets with 
* on the water, with its finger-like pseudopodia, thus ingulf- 
ing them into the jelly. After absorbing the nutriment 
out of the particle, the shells and other waste portions are 
excreted by simply flowing away and leaving them behind. 
The Amoeba reproduces itself by splitting into two parts, 
each of which grows to be an animal like the parent. 
(2) Paramecium,—This is a minute slipper-shaped animalcule, which 
swims rapidly about in stagnant water by means of little 
hair-like processes known as cilia. These cilia also serve to 
sweep food particles to one particular spot in the body 
which serves as a mouth. Reproduction, which is often 
preceded by the temporary joining up of two individuals, is 
brought about much asin the case of the Amawba. (See 
practical work.) 
(8) Torticelia.—This is a little transparent bell-shaped animaleule 
common in stagnant water. It usually has a contractile 
stalk, with which it anchors itself to weeds. Like Parame- 
cium, it is provided with numerous hair-like cilia, which it 
uses much in the same way. I+ reproduces itself by simply 
splitting into two, also by the joining up of a small free 
swimming individual with a larger attached individual, 
followed by a period of rest and ultimate division into 
numerous minute spores, each of which eventually deve- 
lopes into an animal like the parent. (See practical work.) 
Besides such simple types as dmeba, Paramecium, and Forticella, 
we may notice Noctiluca, which has luminous protoplasm and sometimes 
yises in such numbers to the surface of the sea as to give a phospho- 
