NATURAL IMMUNITY. 



only need such knowledge as will serve to help 

 us to keep healthy ourselves and to aid us in 

 our profession as care-takers of the sick. 



With regard to acquired immunity which Acquired 

 comes to us as a result of one attack of a com- "^'"""•*y- 

 municable disease. It has already been stated 

 that in some instances our recovery is due to 

 the death from starvation of the germs of that 

 disease, for the reason that they have consumed 

 all the suitable nourishment that existed within 

 us. We not only recover, but are left pro- 

 tected (immune), for a time from a recurrence 

 of that particular disease. Or, instead of death 

 arising from starvation, sometimes the germs 

 have over-reached themselves in their work of 

 destruction and have produced within us a 

 toxin or poison which proves to be a source of 

 death to themselves and of protection or im- 

 munity to us. In some diseases we are im- 

 mune for years, sometimes for life. In other 

 diseases the state of being immune may be only 

 short lived. Lasting immunity is usually af- 

 forded by one attack of such diseases as small- 

 pox, scarlet fever, measles, typhoid fever or 

 plague. While in pneumonia, diphtheria, 

 cholera, etc., the protection afforded us by one 

 attack is often very brief, and seems rather to 

 predispose to other attacks. 



In artificial immunity, Metchnikoff teaches Artificial 

 that when antitoxins are injected into a subject, '"'"""'*y- 

 57 



