76 INFLAMMATION. 
How are the different forms of inflammation most conveniently 
classified ? 
Into exudative, productive, tubercular, and syphilitic inflammation, 
What are the changes in exudative inflammation ? 
The changes are vascular (as described heretofore), with the pro- 
duction of fibrin, serum and pus. In its simplest form there is little 
or no change in surrounding tissues. The trouble is transitory, simply 
interfering with the affected part fora short time. In the more severe 
forms there is an excessive production of pus cells, producing the 
so-called purulent or suppurating form of inflammation. 
To what is suppurative inflammation usually due ? 
To the presence and growth in the tissue of bacteria (to be described 
hereafter). In this form of inflammation, in connective tissue, there is 
congestion, exudation of serum, emigration of white-blood cells, and 
death of portions of tissue. This dead tissue breaks down and becomes 
fluid. If this change takes place in the substance of a tissue, cavities 
called abscesses are formed which contain pus, serum and fragments 
of necrotic tissue. If occurring on a free surface these materials are 
cast off directly, leaving a cavity called an ulcer. In the viscera, beside 
these changes, the cells of the affected viscus degenerate and may break 
down. 
What are the peculiar characteristics of some forms of exudative 
inflammation on mucous surfaces ? 
The inflammation may be characterized by an excessive production 
of fibrin forming a false membrane over the free surface of the tissue. 
When lying directly on the surface without implicating the superficial 
cells of the mucous membrane it can readily be stripped off, causing 
little or no hemorrhage. Such a membrane is called croupous. When 
the fibrin forming the membrane infiltrates and involves the epithe- 
lium, these cells pass into a condition of coagulation necrosis and form 
a part of the false membrane. Such a membrane is called diphther- 
itic, and when stripped off leaves a raw or bleeding surface. 
What is productive inflammation ? 
It is a form of inflammation in which the product is new connective 
tissue, with little or no congestion and exudation. There are two 
forms—acute and chronic. In the acute form new connective-tissue 
cells are the only product. This form occurs most frequently in the 
peritoneum and pia mater. In the chronic form the product is new 
