RELATION OF BACTERIA TO DISEASE. {101 
would find that certain varieties are capable of develop- 
ing and thereby producing disease only on the mucous 
membrane of the throat, others of the intestine, others 
of the urethra ; some develop only in a wound or in 
the blood, while others, again, under favorable condi- 
tions, seem able to grow in or upon almost any region 
of the body. 
