DISSEMINATION OF ORGANISMS 225 



tioned show that this route cannot be excluded in inflam- 

 mations of the lung. 



D. Alinientary Tract. — The alimentary tract affords the 

 ordinary path of entrance for the causal microbes of many 

 of the diseases of animals and man, since they are carried 

 into the body most commonly and most abundantly in the 

 food .and drink. 



(a) The stomach is rarely the seat of local infection, even 

 in ruminants, except as the result of trauma. The character 

 of the epithelium in the rumen, reticulum and omasum in 

 ruminants, the hydrochloric acid in the abomasum and in 

 the stomachs of animals generally are usually sufiicient pro- 

 tection. Occasionally anthrax "pustules" develop in the 

 gastric mucosa. (The author saw nine such pustules in a 

 case of anthrax in a man.) 



(b) The intestines are frequently the seat of localized 

 infections, as various "choleras" and "dysenteries" in men 

 and many animals, anthrax, tuberculosis, Johne's disease. 

 Here doubtless enter the organisms causing "hemorrhagic 

 septicemias" in many classes of animals, and many others. 

 These various organisms must have passed through the 

 stomach and the question at once arises, why did the HCl 

 not destroy them? It must be remembered that the acid 

 is present only during stomach digestion, and that liquids 

 taken on an "empty stomach" pass through rapidly and 

 any organisms present are not subjected to the action of 

 the acid. Also spores generally resist the acid. Other 

 organisms may pass through the stomach within masses of 

 undigested food. The fact that digestion is 'going on in the 

 stomach of ruminants practically all the time may explain 

 the relative freedom of adult animals of this class from 

 "choleras" and "dysenteries." 



Dissemination of Organisms. — Dissemination of organisms 

 within the tissues occurs either through the lymph channels 

 or the bloodvessels or both. If through the lymph vessels 

 only it is usually much more restricted in extent, or much 

 more slowly disseminated, while blood dissemination is 

 characterized by the number of organs involved simul- 

 taneously. 

 X5 



