CHAPTER I 



INTRODUCTION 



The purpose of this writing is to state the essential facts of infec- 

 tion and immunity accurately and simply, so that they may be under- 

 stood by the intelligent, non-professional man. The reduction and 

 ultimate eradication of unnecessary disease and the consequent pro- 

 longation of life with improved health constitute a patriotic obligation 

 which every citizen should strive to appreciate and to do his part in 

 its performance. 



The further developments of medicine, both curative and pre- 

 ventive, depend on scientific investigations. The public is the bene- 

 ficiary and should in every way encourage medical research. By the 

 application of discoveries already made, the burden of disease has 

 been lightened, sickness has become less frequent and less prolonged, 

 a greater degree of health has been secured, the efficiency of the 

 individual and of the nation has been increased, and life has been 

 lengthened and made more enjoyable. The Federal government and 

 the states should sustain and promote scientific research. That gov- 

 ernment is the best which secures for its citizens the greatest freedom 

 from disease, the highest degree of health and the longest life, and that 

 people which most fully secures the enjoyment of these blessings will 

 dominate the world. 



Medicine consists of the application of scientific discovery to the 

 prevention and cure of disease. All else which may go under the 

 name of medicine is sham and fraud. Without advancement in the 

 physical, chemical, and biologic sciences, there can be no progressive 

 movement in medicine. Scientific knowledge is gained only by obser- 

 vation and experiment. Before the time of Jenner, we are told by 

 the historian, it was unusual to meet in London one whose face was 

 not marked by smallpox. There was a popular belief that one who 

 had cowpox was immune to smallpox. Jenner put this belief to a 

 scientific test. The result was the discovery of vaccination, and this 

 secured the abolition of this disfigurement and a marked reduction 

 in mortality. In 1849, a village doctor, with a crude microscope, 



