ISABEL MULFORD. PAT 
water, in the air we breathe. They find their appropri- 
ate soil, and stand ready to seize upon any and every 
form of waste or lifeless organic matter. The yeast 
plant is nourished by the saccharine material it gets 
from the flour, and it gives off carbonic dioxide and al- 
cohol. The vinegar plant feedsupon the wine and gives 
off acetic acid and water. Thus these lowly organisms 
reduce the higher complex substances to simpler ones, 
and ina body undergoing decomposition one form suc- 
ceeds another until at last the elemental state is reached, 
and the constituent parts of the body are ready to be 
used again by the green plants, aptly called the archi- 
tects of the universe. They and they only have the 
power of taking inorganic materials from the earth, air, 
and water, and converting them into living organic 
tissues. 
The bacteria have done a large part of the work of re- 
moving the old trunks of trees and other débris of dead 
plants and animals which otherwise would have accu- 
mulated through the long ages. It is claimed that 
without bacteria we should have no fertile soil, no rich 
harvests. They render it possible to use the soil over 
and over again, and thus secure to us a constant suc- 
cession of useful plants. 
Bacteria cause the waters of close reservoirs to work 
and thus render the water sweet and clear for our use. 
Bacteria rot flax and release the fibre for the manutac- 
tory. They cause diseases of noxious insects and thus 
reduce their numbers. Either bacteria or the yeast 
plants, are the active agents in the various forms of 
fermentation, and so supply us with bread, beer, wine, 
and vinegar. 
Against these good offices we must offset the fact that 
certain forms of bacteria are always found as an ac- 
companiment of some of the most virulent diseases of 
mankind and the domestic animals. 
31 aL SL 
