INFECTION AND INTOXICA TION 83 



that in these cases there may have been a lesion long 

 antedating the present trouble, and now healed, by 

 which the passage of the bacteria into the blood may 

 have been made easy. 



Intestinal infection by external bacteria, such as is 

 observed in typhoid fever and cholera, probably takes 

 place by the growth of the respective bacteria in the 

 intestinal contents, the generation of their respective 

 toxic products, their absorption, and a subsequent vital 

 depression that permits of an action upon the tissues 

 which could not have occurred primarily. . 



The anthrax bacillus seems capable of effecting an 

 entrance into the tissues without opposition. Developing 

 in the intestine in large numbers, it surrounds the villi 

 with thick networks of bacillary threads, works its way 

 into the lymphatics, and leads to a general infection. 



4. The placenta is sometimes a source of infection, and 

 in exanthematous diseases, such as variola and measles, 

 and in anthrax, symptomatic anthrax, glanders, syphilis, 

 relapsing fever, typhoid fever, and, in rare cases, tuber- 

 culosis, it seems to be pretty clearly demonstrated that 

 the cause of disease can transfer itself from the mother 

 to the offspring, either without a lesion or by the pre- 

 liminary formation of a lesion in the placenta. 



Forms of Bacterial Pathogenesis. — In general, it 

 may be said that pathogenesis depends chiefly upon the 

 ability of the micro-organisms to manufacture injurious 

 substances. As, however, the clinical pictures resulting 

 from infection and experimental intoxication produced 

 by the injection of the separated bacterial poison into an 

 animal are frequently very different, we must conclude 

 that intoxication is but a part of infection, which in real- 

 ity consists of the sum of all the vital phenomena mani- 

 fested by the bacterium in its parasitic life. 



As infection is so markedly influenced by the viru- 

 lence, number, avenue of entrance, and condition of the 

 subject, it is far from being a process that takes place 

 with regularity. For most infections there is a type 



