Suppuration is of three kinds: phlegmonous, caseous, and thin pus.

Phlegmonous pus--or what is known as laudable pus--is a yellowish-white, creamy, thick, odorless liquid. It is met with in phlegmons and suppurating pleurisies.

Caseous pus resembles soft cheese.

Thin pus is a serous liquid which exhales a fetid odor.

The color of pus varies from a light yellow to an orange, brownish red, or greenish. The coloring may be from bile or blood.

Pus in sputum sinks in water, Pus in urine precipitates with the addition of ammonia. The microscope will reveal pus cells.

Bacteriology gives many pyrogenic agents, but there is much distinction without differences. A ferment and a protein end in fermentation, inflammation, and suppuration. The chemistry of the compound does the rest. Chemistry is the determining factor.