MIXED INFECTIONS. 591 



by connective tissue (tuberculous scar), or partial caseation, 



.,, ,. V 10. / i -r. , v XT 4. Calcification 



impregnation with lime salts (calcification). Not mi Liqu>- 



infrequently the caseous portion of a nodule under- fact 



goes liquefaction, which some have referred to the 



action of proteolytic ferments. The contents of 



such foci finally become sterile. In the event that 



healing of this nature does not occur, the infection 



is transmitted to other organs as described above. 



The temperature, loss of weight, fever, increased !^ c ^ e 1 fa ap and 

 cardiac action, and arteriosclerosis which are seen Disturbances. 

 in tuberculosis indicate that the products of the 

 bacillus have a profound effect on the functions 

 of the body, and produce great disturbances in 

 metabolism, although they seem to have no marked 

 selective action for particular tissues. Many dis- 

 turbances are secondary to changes produced in 

 particular organs and are not referable to specific 

 action of the toxins, such as those which are 

 consequent on poor oxygenation in pulmonary 

 tuberculosis, and the amyloid degeneration which 

 follows prolonged suppurative tuberculosis. 



Mixed infection, especially with the streptococ- Mixed 

 cus, plays a very important part in the course of ] 

 pulmonary tuberculosis, especially in the caseous 

 and cavernous forms. Staphylococci. B. pyocya- 

 neus, various diplococci, the pneumococcus, bacil- 

 lus of Friedlander, diphtheria and pseudo-diph- 

 theria bacilli, and the influenza bacillus are also 

 found as secondary organisms in pulmonary tuber- 

 culosis. Some of them invade the surrounding 

 healthy tissue, cause lobular consolidations, and in 

 this way probably prepare a favorable soil for 

 further extension of the tuberculous process. They 

 doubtless hasten the liquefaction of caseated tissue, 

 a step in the formation of abscesses. The high and 



