262 BACTERIOLOGY. 



The third question is this : Do the same 

 " specific " disease germs affect all animals 

 with the same typical disease ? This question 

 must also be answered in the negative. We 

 see that each kind of disease germ affects only 

 certain hosts ; syphilis, leprosy, cholera and 

 typhoid fever are known only in man, while 

 tuberculosis, glanders and anthrax attack 

 both man and certain kinds of animals. 

 Further illustrations are given on p. 243 and 

 in the chapter treating of the individual species 

 of bacteria ; others will be brought forward 

 later. 



The fourth question is, Does a " specific " 

 disease germ cause only one disease ? We 

 may distinguish in this inquiry two groups 

 of phenomena. In the first group belong those 

 facts showing that similar symptoms may be 

 evoked and that the same organs or tissues 

 may suffer anatomically similar changes 

 through the action of entirely different germs. 

 For example, the formation of nodules or tu- 

 bercles in connective tissue may be brought 

 about by the germs of syphilis, leprosy, gland- 

 ers, and tuberculosis ; suppiiration can be 

 caused by the germs of wound erysipelas, the 

 tubercle bacilli, the anthrax bacilli, and the 

 germs of typhoid fever and pneumonia ; both 

 the common bacteria of the colon and the chol- 



