IMMUNITY 233 



produced within the body of the patient can be neutral- 

 ized directly without the necessity of waiting for the 

 cells to react and produce anti-toxin. 



Immunity. — Most disease-producing organisms re- 

 tain within their own bodies the poisons which they 

 produce and only give them up as they are destroyed. 

 In order to combat these successfully the body cells must 

 do more than produce the anti-toxin for the neutraliza- 

 tion of poison. They must produce in addition anti- 

 bodies which attack and destroy the organisms them- 

 selves. This actually happens, so that one who is ill 

 from such a disease as pneumonia is producing within 

 his tissue anti-bodies which are actively destructive to 

 the pneumonia organisms as well as able to neutralize 

 the poisons which the organisms produce. 



Smallpox and Vaccination. — An account of im- 

 munity would be incomplete without brief reference to 

 smallpox. Two hundred years ago this loathsome disease 

 was so prevalent throughout the civilized world that 

 adults with un-pock-marked faces were objects of public 

 attention. A certain famous beauty, Lady Mary 

 Montagu, went so far as to adopt a practice well known 

 in Constantinople, of having herself infected with small- 

 pox, it having been observed that persons who survived 

 deliberate infections escaped with less pock-marking 

 than the general run of victims of the disease. Where 

 pock-marked faces were so prevalent, the current belief 

 that milkmaids were more likely than other persons to 

 have smooth skins was bound to attract considerable 

 wB attention. Jenner, a young physician who looked into 

 H| the matter shortly before the end of the Eighteenth 

 ^B Century, became convinced that there was some real re- 

 ^B lation between the sores which milkmaids frequently 

 ^B got on the palms of their hands from the udders of cows 

 ^B afflicted with cowpox and their relative immunity to 

 ^B smallpox. Following up this idea, he prevailed upon the 



