108 BOTANY. 
naked masses of protoplasm again, thus completing the 
round of life (Fig. 45). 
There are seven orders of Slime-moulds, which are distinguished 
mainly by their structure in the spore-bearing stage. Many species 
occur in all parts of the United States, and may be readily found on 
decaying logs, stumps, etc., and on the bark-covered ground in tan- 
yards. A fine large one—Fuligo varians—is especially common in 
the last-named situation. 
Crass JI. Bacreria anp Yuast-Piants (Schizomycetes). 
221. The plants of this class are minute cells, each con- 
sisting of a mass of protoplasm surrounded by a thin wall. 
The cells cohere but little, and in some cases not at all. 
They contain no chlorophyll, and always live in solutions 
of nourishing matter. Two orders are generally recog- 
nized, the one containing the Bacteria, and the second the 
Yeast-plants. 
222. Bacteria.—These are the smallest of living things. 
Their minute cells in some cases méasure no more than 
.0005 mm. (z5455 inch) in diameter. They are in some 
species rounded in shape, in others elongated like little 
rods, or in others more or less curved (Fig. 46). They are 
frequently provided with one or two cilia (i.e., whip-like 
projections of protoplasm), by means of which they move 
about with great activity. 
223. Bacteria are found in great numbers in the watery 
parts of decaying organic matter, causing various kinds of 
fermentation. They reproduce by fission with such aston- 
ishing rapidity that in a short time they swarm in any ex- 
posed substance which is capable of furnishing them with 
food. Some of the species live in the watery juices of 
plants and animals, causing various diseases. 
224, Some bacteria can endure high temperatures, and 
