Extension uf Disease; Termimition of Disease. 99 



system {sympathetic or consecutive lesions). By the term exten- 

 sion by continuity is understood the progress of the pathological 

 process upon the surfaces in continuity and along uninterrupted 

 tissues in the immediate vicinity of the original focus, as along 

 the mucous membrane of the nose to the frontal and maxillary 

 sinuses, from the pharynx to the Eustachian tubes and middle 

 ears. Extension by contigxiity occurs from one surface to that of 

 an adjacent organ in contact with the first, as from the. visceral 

 pleura to the costal pleura, from the serous surface of the stomach 

 to the liver. The explanation for such a mode of extension is 

 mainly to be found in the fact that the pathogenic agent finds 

 some particular opportunity for invading such adjacent tissues; 

 thus bacteria may pass to an adjoining structure, be swept along 

 by its fluids and spread widely. A suppurative or gangrenous 

 focus in the lung may in some such manner gain access to the 

 pleura; the latter may rupture and the microorganisms, spread 

 over the entire pleural surface from the respiratory movements, 

 mav give rise to an extensive pleuritis. Hccmatogenous extension 

 of a disease occurs when the pathogenic agents gain access to the 

 blood; IxmpJwgcnous cxtcnsioji. when such influences, through 

 the agency of the wandering cells, are mingled with the lymph 

 (cf. emboHsm). Sympathetic disturbances in function arc appar- 

 entlv in part the result of sensory and motor reflex action, in 

 part the result of primary changes, the etficiency of one organ 

 depending upon the functional integrity of another, as a chronic 

 hepatic cirrhosis induces cardiac hypertrophy and splenic cyanosis 

 by the circulatory disturbances which it produces. 



Coincidence of diseases may occur entirely independently of any 

 relation between the processes, or may depend upon some connec- 

 tion ; where this occurs complications are said to exist. Thus 

 swine-erysipelas is often complicated by valvular endocarditis (the 

 infectious germs invading the latter structures), o'- suppurative 

 osteitis of the cranium may be complicated by a meningitis 

 (through extension of the suppuration by contiguity to the 

 meninges). 



The termination of disease may result in one of three ways: 



1. Recovery, cure or restoration, complete re-establishment 

 of the disturbed function and condition of the organ ; 



2. Incomplete recovery, with appearance of secondary affec- 

 tions, persistence of sequels or defects ; or 



3. Death of the individual. 



