CHAPTER IV. 



General Question of Immunity. 



Warfare is a necessary condition of existence. The 

 striif^gle is not only between different animals of like 

 size but also between the largest of animals and the 

 smallest of microscopic bacteria. The weapons of 

 defence in the two instances are, however, different : 

 teeth, horns and claws for the one foe ; antiseptic secre- 

 tions and phagocytic cells for the other. 



The anti-bacterial weapons are produced for the 

 most part in certain restricted areas of the body and 

 distributed throughout the blood stream. The chief 

 anti-bacterial factories are the spleen* (Luckhardt and 

 Beckt, 1911), the marrow and the lymphatic glands. 

 These three are normally concerned in the destruction 

 of waste products (poisons arising within the body), 

 the first two concerned with purifying the blood, the 

 third with purifying the lymph. * 



When bacteria and their toxins (poisons introduced 

 from outside the body) appear on the scene it is natural 

 that their removal should fall to these same organs, 

 which react by a great excess production of anti-toxins, 

 bacteriolysins and specially equipped leucocytes 

 which pour into the blood stream to the general pro- 

 tection of the body. 



* And other haemo-lvniph glands. 



12 



