42 FISTULA AND POLL-EVIL 
as is seen in some cases of fistula long before 
infection has entered into the situation. 
Summarizing the condition during the sac- 
cular stage we find a sac containing a sero- 
fibrinous, sterile exudate, that may be large 
and surrounded by a thin capsule or small and 
enclosed in a very thick mass of connective tis- 
sue. Between these two extremes we find the 
intermediate varieties—for example, one the 
size of a child’s head containing a quart of 
fluid and encapsulated with a fibrous envelope 
one inch in thickness; another the size of a foot- 
ball with only a very thin wall; and finally, a 
rare case with a very insignificant cavity sur- 
rounded with a great volume of connective 
tissue. Pathologically all of these are similar, 
they differ only in the relative quantities of 
the different elements entering into their con- 
stituent parts. 
During this stage fistula is a benign disease. 
It is not as yet infectious. There is no syste- 
matic disorder. The patient suffers no appar- 
ent inconvenience. Its general health is 
undisturbed. 
Until now the process belongs to an order of 
pathological conditions no more understood 
than the growth of tumors. In fact, it re- 
sembles tumor and cyst formation in all 
respects. It is but cellular activity around a 
