106 IMMUNITY IN HEALTH 



close connection with the chief collections of bacteria 

 lying outside of, but adjacent to, the tissues. 

 Physiological : — 



(1) The subepithelial lymphatic glands in health are 

 continually ingesting bacteria in enormous numbers. 

 By all we know of the production of artificial immunity 

 this ingestion of bacteria must enhance the general 

 powers of the organism against these bacteria. 



(2) Mere exposure to cases of infectious diseases often 

 serves to confer immunity even in those who do not 

 contract the complaint. 



(3) The subepithelial lymphatic glands are largest 

 and most active in young children at a period when 

 individuals are acquiring immunity to the various com- 

 mon infections. In old age all lymphatic structures 

 tend to atrophy. 



Clinical : — 



(1) The subepithelial glands bear the brunt of the 

 attack in faucial and intestinal infections. Scarlet 

 fever, typhoid fever, and appendicitis are sound exam- 

 ples. In infantile enteritis the Peyer's patches are 

 swollen and infected. As a rule, the tissue which is 

 most seriously attacked provides the greatest number 

 of antibodies. For instance, the power of brain emul- 

 sions to neutralise tetanus toxin has been satisfactorily 

 proved. (Ehrlich, 1906.) 



(2) The subepithelial glands hypertrophy as a result 

 of repeated infectious diseases. Whooping-cough, 

 scarlet fever, measles, and " colds " (especially if asso- 

 ciated w^ith deficient exercise or unhygienic surround- 

 ings) lead to enlargement of tonsils and adenoids. 



(3) It is often observed during scarlatinal epidemics 

 that a person may apparently secure immunity by a 

 very mild tonsilitis which is unaccompanied by rash, 

 malaise, or other signs of general injury. 



(4) In fulminating infections, where septicaemia is 



