NATURAL IMM;UNITY. 



isms and then the disease is starved out 

 Sometimes the action of the germs upon the 

 cells of the body produces a condition which is 

 poisonous to the germs themselves and thus 

 they are destroyed by the products of their own 

 tdtal activities. In either case the tissues are 

 left in a state of immunity from that particulai '"'"""ity- 

 disease for a longer or shorter period, some- 

 times for life. We are told of three forms ol 

 immunity. 



I. — Natural immunity, which is the natural Natural 

 and constant resistance of the antagonistic cells 

 or. phogacytes to the development within the 

 body of pathogenic bacteria. 



II. — Acquired immunity, which is that im- Acquired 

 munity given to the body, or which the bodj 

 gains, by a single attack of a certain com- 

 municable disease. 



III. — Artificial immuity, which is that im- Artificial 

 munity given to, or gained by the body, through 

 the use of antitoxins. 



Immunity. 



NATURAL IMMUNITY. 



Let US look into the subject of natural im 

 munity and the part played therein by several 

 allies to the phagocytes. 



First, let us consider the protection afforded 

 the healthy human body by its inner and outei ■ 

 surfaces. 



SI 



