Soil Changes Produced By Micro-organisms. 
39 
Pig. l. 
Fig. 2. 
Fig. 3. 
Fig. 4. 
Fig. 5. 
Fig. 6. 
Fig. 1. 
Fig. 2. 
Fig. 3. 
Fig. 4. 
Fig. 5. 
Fig. 6. 
Fig. 1. 
Fig. 2. 
Fig. 3. 
Fig. 4. 
Fig. 5. 
Fig. 6. 
EXPLANATION OF PLATES. 
Plate I. 
Staphylococcus pyogenes aureus, a pus-forming coccus; magnified 
1000 times. 
Azotobacter chroococcum, a non-symbiotic nitrogen fixing coc¬ 
cus; magnified 100 0 times. 
Bacterium mycoides, a denitrifying bacterium (rod type) found 
in soil; magnified 1000 times. 
Spirillum rubrum, a harmless spirillum found in water; mag¬ 
nified 1000 times. 
Saccharomyces cerevisiae, the yeast cells from compressed 
yeast; magnified 1000 times. 
Spores of Penicillium glaucum, the common blue mold on canned 
fruit; magnified 1000 times. 
Plate II. 
Colony of Bacterium mycoides. 
Colony of Bacterium tuberculosis (human). 
Colony of Pseudomonas medicaginis, the cause of the stem 
blight of alfalfa. 
Colony of Bacterium diphtheriae (human). 
Colony of Sphaerella rubina, a fungus or mold causing the spur 
blight of red raspberries. 
Colony of Azotobacter chroococcum. 
Plate IIP 
A pure culture of Bacillus amylovorus, the germ of pear blight. 
Note the similarity of the colonies in a pure culture. 
A mixed culture. Note the unlike character of the colonies in 
a mixed culture. 
Colonies of bacteria from soil. 
Colonies of bacteria from water. 
Colonies of bacteria and molds from dust. 
Colonies of bacteria from air. 
