CHAPTER X. 



THE RELATION OF BACTERIA TO DIPHTHERIA, 

 PNEUMONIA, SCARLET-FEVER, ETC. 



THERE are several diseases besides those 

 which we have considered in some de- 

 tail which are proven to be caused by the 

 entrance of bacteria into the body. There is 

 a still larger number which we believe, and 

 with the very best of reasons, to be caused by 

 bacteria, but from which the germs have not 

 yet been isolated and carefully studied so that 

 we can speak positively about them. 



Diphtheria. 



Diphtheria is one of the most dreaded of 

 the diseases, especially in childhood, which are 

 known to be caused by bacteria. We are not 

 yet quite certain whether it is always caused 

 by one form of germs, or whether in the differ- 

 ent outbreaks or in different regions sometimes 







