74, A LABORATORY MANUAL OF BOTANY 
show how the plant body of Cladophora is better fitted for 
growth than Spirogyra. Is it an advantage for Cladophora 
to be attached to a support? Can it grow where Spirogyra 
could not? Of what advantage to the plant is it to have 
spores which can swim? 
These zoospores are very much simpler than the zygo- 
spores of Spirogyra. Why are they said to be so? 
LESSON XXxXTX 
Vaucheria ! 
General study.—This plant is almost always found in 
greenhouses, on the damp earth under benches and in pots; 
out-of-doors it may be found on earth in damp, shady places, 
and sometimes floating upon quiet water. 
It forms a heavy green felt-like mat, and is so large that 
many of its characteristics may be seen without magnifica- 
tion. About a week before the plant is to be studied two 
or three mats should be thrown into a dish of water and 
placed near the laboratory window, when quite favorable 
material will develop. 
Vegetative structure——Does the plant branch? Is it 
divided by cell-walls? A plant containing many nuclei not 
separated from one another by walls is called a cenocyte. 
How are the plastids arranged? How are new plastids 
formed? Draw a part of one plant. 
Reproduction—(a) Reproduction by zoospores—asexual 
reproduction. 
Note the end of a branch where a large region has been 
cut off by a wall. The enclosed mass forms one very large 
zoospore. Note how these move about when they are set 
free. Try to find some just beginning to grow. Draw. 
(b) Reproduction by gametes—sexual reproduction. 
Note outgrowths from side of filament. These may be 
1 Gidogonium may be used instead of Vaucheria. 
