32 INFECTIOUS AND PARASITIC DISEASES. 



surgeon, in operating for the removal of malignant 

 tumors or for some other urgent cause, does his utmost 

 when the dangerous condition for which he operates 

 is removed. But how much would his surgery avail, 

 if the body did not potentially possess amazing powers 

 for repair and reconstruction?* 



Nearly all complications occurring in the 

 course of diseases, whether they be infec- 



TIONS. . r • 1 



tious or non-mfectious, are due to mfec- 

 tious agents; and the infectious agents principally at 

 fault are bacteria. The source of the infecting bacteria 

 depends upon circumstance. It may happen that the 

 agent has its habitat upon the individual's integument, 

 or within a cavity of the body leading to the exterior. 

 Thus, pneumonia, occurring as a complication, is 

 caused by the pneumococcus, a micro-organism that 

 almost everyone harbors in his mouth even in health. 

 An instance of contamination from the integument is 

 afforded by furunculosis (boils), a common sequel to 

 various infections during or after convalescence is 

 established. 



A second source for bacteria which complicate 

 disease, is found in objects, insects, and persons that 

 come in contact with the patient. Thus wounds 

 soiled with earth are those in which tetanus (lock-jaw), 

 and gaseous gangrene, are liable to develop, because 

 the bacteria which bring about these infections have 



* See Chapter on Inflammation. 



