THE ALG 43 
Its general character may be studied best in the laboratory 
by placing a stick or stone supporting some of the plants in 
a dish of water. By observation and handling determine 
its general characters as compared with Spirogyra. 
Vegetative structures.—Mount and examine. Has the 
plant distinctly organized basal and apical regions? Is it 
a simple straight thread as Spirogyra? Make a sketch show- 
ing the general structure of the plant. Study one or two 
cells in detail, and draw. 
Reproduction.—If some Cladophora plants are kept in a 
dish containing a little water, and in a dark place, repro- 
ductive bodies may be formed. At such times certain cells 
have their nuclei divided into large numbers. 
Around each of these nuclei a mass of cytoplasm is or- 
ganized, and the result is a distinct, pear-shaped body. At 
the smaller end there are formed two fine hair-like exten- 
sions known as cilia, which serve to move the whole cell 
about. These bodies are so small and have such a rapid 
movement that they are not easily seen. They finally escape 
from the cell that formed them—their mother-cell—and after 
swimming about for a while attach themselves to some sup- 
port and grow, becoming new plants similar to the parents. 
Therefore these swimming bodies are spores, and since they 
swim they are called zoospores, which means “ animal 
spores.” They are unlike the zygospores of Spirogyra, 
since they are not formed by the union of gametes, but they 
are like them in having the power of reproducing the parent- 
plant. A cell which produces spores from its contents 
directly (no cell union) is a sporangium. 
Study your material, and draw, showing as much of the 
process of reproduction as you can. Put some of the 
zoospore material in a favorable place and examine from day 
to day to see the development of new plants. 
General suggestions—Bearing in mind that plants must 
have their chlorophyll exposed to the light in order to grow, 
