56 FISTULA AND POLL-EVIL 



a well defined limiting wall is likewise not un- 

 derstood. It simulates tumor formation. 



3. Typical fistulae develop deep secondary 

 abscess during the early phase of the phleg- 

 monous stage, while atypical ones develop these 

 only in the later stages. The early abscess 

 cavities of the latter are superficial. 



4. Fibrosis, that is, the formation of fibrous 

 tissue is more pronounced in the typical form 

 and is never voluminous in the other. 



5. Bone involvement is more certain and al- 

 ways more extensive in the atypical forms. 



6. The toxemia is more pronounced in the 

 early stages of the typical form, but in later 

 stages both are alike in this connection. 



